Short and long interpregnancy intervals: correlates and variations by pregnancy timing among U.S. women

Birth Spacing and Child Maltreatment: Population-Level Estimates for North Carolina

We examine population-level associations between birth spacing and child maltreatment using birth records and child welfare records for 1,099,230 second or higher parity children born in North Carolina between 1997 and 2013. Building upon previous research, administrative data linkages were used to address out-of-state migration and family-level heterogeneity in birth spacing and child maltreatment risk factors. Findings provide the strongest evidence to date that very short birth spacing of zero through 6 months from last birth to the index child's conception is a prenatal predictor of child maltreatment (indexed as child welfare involvement) throughout early childhood. Consequently, information about optimal family planning during the postpartum period should become a standard component of universal and targeted child maltreatment prevention programs. However, challenging previous empirical evidence, this study reports inconsistent results for benefits of additional spacing delay beyond 6 months with regard to child maltreatment risk reduction, especially for children of racial and ethnic minorities. These findings call for further inquiry about the mechanisms driving the connections between birth spacing and Child Protective Services assessments.

Reducing stunting and underweight through mother's birth spacing: evidence from Ghana

BACKGROUND

Researchers over the years have underscored the role of birth spacing on maternal health, however, inadequate maternal repletion due to shorter birth intervals could also affect the health of the child. Even so, limited studies exist on the linkage between birth spacing and child nutrition. This study examines the association between birth spacing and child stunting and underweight using the 2014 Ghana Demographic and Health Survey.

METHODS

The study sourced data on 1, 904 children less than 59 months from the 2014 Ghana Demographic and Health Survey. The study employed bivariate analysis and logistic regressions to establish the association between birth spacing, and child stunting and underweight.

RESULTS

The analyses reveal that childbirth spacing between 24 and 35 months (OR = 0.62, 95% CI: 0.38-0.99; p < 0.05), 36 to 47 months (OR = 0.42, 95% CI: 0.25-0.70; p < 0 0.01), and beyond 47 months (OR = 0.47, 95% CI: 0.28-0.78; p < 0.01) have lower odds of child stunting than children with birth spacing less than 24 months. Children with birth spacing between 24 and 35 months (OR = 0.53, 95% CI: 0.29-0.98; p < 0.05), 36 to 47 months (OR = 0.44, 95% CI: 0.22-0.90; p < 0.01) and beyond 47 months (OR = 0.49, 95% CI: 0.26-0.94; P < 0.05) have lower odds of being underweight than those with birth spacing less than 24 months.

CONCLUSION

The study reveals that mothers with a birth spacing of at least two to three years compared to their counterparts with less than two years of birth spacing have lower odds of having a stunted and underweight child under age five. The study recommends that Ghana Health Service and other healthcare providers should educate mothers on the gains of birth spacing of at least two years on their children.

Associations of unintended pregnancy with autism spectrum disorders and the modification of folic acid supplements

There is limited evidence on the associations of unintended pregnancy with autism spectrum disorders (ASD). This study aimed to examine this relationship and the modification of pre-conceptional and prenatal folic acid supplements. Six thousand and five toddlers aged 16 to 30 months from seven cities of six provinces in China were eligible for participation. Information on unintended pregnancy and folic acid supplements was obtained via questionnaires from caregivers of toddlers. The diagnosis of ASD was based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the Chinese version of the Childhood Autism Rating Scale (CARS). Of the 6005 toddlers in the study (3337 boys and 2668 girls), 71 (1.18%) received the diagnosis of ASD. Generalized linear models with a logit link function showed unintended pregnancy was positively associated with ASD (odds ratios [OR] = 1.69, 95% confidence interval [CI], 1.05-2.79). Stratified estimates indicated that the association remained stable among toddlers of mothers without pre-conceptional and prenatal folic acid supplements (OR = 2.75, 95% CI, 1.04-7.27; n = 1243, 20.70%). Unintended pregnancy was associated with higher odds of ASD in 16-30 months of toddlers, and the association was consistent among toddlers of mothers without prenatal folic acid supplements. Our findings emphasize the need to raise awareness of the risk of unintended pregnancy and the benefits of folic acid supplements among Chinese women.

Factors associated with fertility intention among women with systemic lupus erythematosus in China: A cross-sectional study

OBJECTIVE

This study aims to explore the status and influencing factors of fertility intention in women of childbearing age with systemic lupus erythematosus (SLE).

METHODS

A total of 158 SLE patients admitted to the Affiliated Hospital of Nantong University from February 2021 to February 2022 were selected for a cross-sectional study. The dependent variable in this study was the fertility intention of lupus women of childbearing age, so the questionnaire was selected: "In view of your disease, do you plan to have children? Yes/no" as the measurement statement. Lupus patients were divided into fertility intention groups and non-fertility intention groups. The questionnaire survey comprises following scales: Hospital Anxiety and Depression Scale (HADS), Multidimensional Fatigue Inventory (MFI-20), Female Sexual Distress Scale-Revised (FSDS-R), and others. Independent t-test, one-way ANOVA, Mann-Whitney U test, and binary logistic regression were used for analysis.

RESULTS

The results showed that 20.9% of lupus patients in this study had a fertility intention. The fertility intention was associated with age, reproductive history, reproductive concerns, sexual distress, fatigue, family function, social support, depression, and sleep. Binary logistic regression showed that physical fatigue (OR 3.56, 95% CI 1.048-12.07) and personal health (OR 2.50, 95% CI 1.065-5.853) had significant predictors of fertility intention.

CONCLUSION

Our study identified a lower fertility intention in SLE patients who had reproductive concerns, sexual distress, family dysfunction, and fatigue. We encourage healthcare institutions to provide counseling services to all the SLE patients who have fertility intention and focus more on those who have requirements for fertility.

The influence of birth outcomes and pregnancy complications on interpregnancy interval: a quantile regression analysis

PURPOSE

To ascertain whether adverse pregnancy outcomes at first pregnancy influence subsequent interpregnancy intervals (IPIs) and whether the size of this effect varies with IPI distribution METHODS: We included 251,892 mothers who gave birth to their first two singletons in Western Australia, from 1980 to 2015. Using quantile regression, we investigated whether gestational diabetes, hypertension, or preeclampsia in the first pregnancy influenced IPI to subsequent pregnancy and whether effects were consistent across the IPI distribution. We considered intervals at the 25th centile of the distribution as 'short' and the 75th centile as 'long'.

RESULTS

The average IPI was 26.6 mo. It was 0.56 mo (95% CI: 0.25-0.88 mo) and 1.12 mo (95% CI: 0.56 - 1.68 mo) longer after preeclampsia, and gestational hypertension respectively. There was insufficient evidence to suggest that the association between previous pregnancy complications and IPI differed by the extent of the interval. However, associations with marital status, race/ethnicity and stillbirth contributed to either shortening or prolonging IPIs differently across the distribution of IPI.

CONCLUSION

Mothers with preeclampsia and gestational hypertension had slightly longer subsequent IPIs than mothers whose pregnancies were not complicated by these conditions. However, the extent of the delay was small (<2 mo).

Association between interpregnancy interval and maternal and neonatal adverse outcomes in women with a cesarean delivery: a population-based study

BACKGROUND

Interpregnancy interval (IPI) has been linked with several maternal and neonatal adverse events in the general population. However, the association between IPI and maternal and neonatal outcomes in women whose first delivery was by cesarean delivery is unclear. We aimed to investigate the association between IPI after cesarean delivery and the risk of maternal and neonatal adverse events.

METHODS

Women (aged ≥ 18 years) whose first delivery was cesarean delivery with 2 consecutive singleton pregnancies from the National Vital Statistics System (NVSS) database between 2017 and 2019 were included in this retrospective cohort study. In this post-hoc analysis, logistic regression analyses were used to examine IPI (≤ 11, 12-17, 18-23 [reference], 24-35, 36-59, and ≥ 60 months) in relation to the risk of repeat cesarean delivery, maternal adverse events (maternal transfusion, ruptured uterus, unplanned hysterectomy, and admission to an intensive care unit), and neonatal adverse events (low birthweight, premature birth, Apgar score at 5 min < 7, and abnormal conditions of the newborn). Stratified analysis based on age (< 35 and ≥ 35 years) and previous preterm birth.

RESULTS

We included 792,094 maternities, 704,244 (88.91%) of which underwent a repeat cesarean delivery, 5,246 (0.66%) women had adverse events, and 144,423 (18.23%) neonates had adverse events. After adjusting for confounders, compared to an IPI of 18-23 months, the IPI of ≤ 11 months [odds ratio (OR) = 1.55, 95% confidence interval (CI): 1.44-1.66], 12-17 months (OR = 1.38, 95%CI: 1.33-1.43), 36-59 months (OR = 1.12, 95%CI: 1.10-1.15), and ≥ 60 months (OR = 1.19, 95%CI: 1.16-1.22) were associated with an increased risk of repeat cesarean delivery. In terms of maternal adverse events, only IPI of ≥ 60 months (OR = 0.85, 95%CI: 0.76-0.95) was observed to be associated with decreased risk of maternal adverse events in women aged < 35 years. In analysis of neonatal adverse events, IPI of ≤ 11 months (OR = 1.14, 95%CI: 1.07-1.21), 12-17 months (OR = 1.07, 95%CI: 1.03-1.10), and ≥ 60 months (OR = 1.05, 95%CI: 1.02-1.08) were related to an increased risk of neonatal adverse events.

CONCLUSION

Both short and long IPI were associated with an increased risk of repeat cesarean delivery and neonatal adverse events, and women < 35 years may benefit from a longer IPI.

Evaluating Shared Decision-Making in Postpartum Contraceptive Counseling Using Objective Structured Clinical Examinations

Background

Shared decision-making (SDM) may support widespread uptake of progestin-containing long-acting reversible contraceptives in the immediate postpartum period. We piloted an Objective Structured Clinical Examination (OSCE) to evaluate first-year obstetrics and gynecology resident physicians' use of SDM in postpartum contraception counseling.

Methods

As part of their 2015 and 2016 OSCEs, first-year OB/GYN residents were instructed to provide contraceptive counseling to a Standardized Patient (SP) portraying a 29-year-old postpartum patient seen during rounds on the morning following her delivery. Three investigators independently scored each resident encounter using a 10-item rubric adapted from a 9-item SDM measure and assigned scores of 0 (absent), 1 (partial), or 2 (complete). Each encounter was video and audio recorded, then transcribed for qualitative analysis. Descriptive statistics was produced using SPSS version 24.

Results

Eighteen residents participated. The majority (78%) discussed contraceptive options and timing of initiation. Nearly 33% elicited factors most important to the SP in influencing her preference. Only 6% discussed the benefits of exclusive breastfeeding, and few addressed the uncertainty of progesterone on milk supply and production.

Conclusion

Although residents conveyed ample clinical information, the vast majority did not discuss elements of SDM, such as her preferences, values, and goals for future fertility and breastfeeding. Our work revealed that critical elements of SDM are often not explored and deliberated by resident physicians. Trainings (e.g., OSCEs) are needed to equip residents with effective communication skills to facilitate more SDM in postpartum contraceptive care.

Maternal factors associated with interbirth intervals in Australia: Results from a population-based longitudinal study

BACKGROUND AND OBJECTIVE

Short and long intervals between successive births are associated with adverse birth outcomes, especially in low-income and middle-income countries, yet the birth intervals in high-income countries remain relatively understudied. The aim was to examine maternal factors associated with birth intervals in Australia.

METHODS

The sample comprised 6130 participants in the Australian Longitudinal Study on Women's Health who were born in 1973-1978, had two or more births, and responded to regular surveys between 1996 and 2018. Interbirth interval (IBI) was defined as the time between successive live births. Maternal factors were examined using accelerated failure time models.

RESULTS

For women with only two births (n = 3802), the median time to the second birth was 34.0 months (IQR 23.1, 46.2) with shorter IBI associated with higher socioeconomic status (eg, university education (31.9 months), less income stress (31.1)), and longer IBI associated with age over 35 (39.7), fair/poor health (43.0), untreated fertility problems (45.5), miscarriage (39.4), or abortion (41.0). For women with three or more births (n = 2328), the median times to the second and third births were 31.2 months (19.9, 42.1) and 36.5 months (25.3, 50.1), respectively; some factors were consistent between the first IBI and second IBI (eg, university education and being married were associated with shorter IBI), whereas income stress was associated with longer first IBI but not with second IBI.

CONCLUSIONS

Understanding maternal factors associated with birth intervals in a high-income country like Australia may enable more nuanced tailoring of guidelines for prepregnancy care.

Impact of interpregnancy intervals on perinatal and neonatal outcomes in a multiethnic Pakistani population

BACKGROUND

Short birth intervals (SBIs) and long birth intervals (LBIs) have been shown to have serious implications for health of both mothers and their children. This study was aimed to investigate the determinants and reproductive outcome of SBI and LBI in a multiethnic Pakistani population.

METHODS

In a cross-sectional prospective study design, 2798 women admitted in a tertiary-care hospital in Islamabad for delivery were recruited and data on second or higher birth order deliveries were collected. Birth intervals were defined as short (&lt;24 months) and long (&gt;36 months). The reproductive outcome was defined in terms of perinatal and neonatal mortalities, and neonatal complications. Univariate and multivariate logistic regression analyses were performed.

RESULTS

Pregnancies with SBI and LBI were observed in 20% and 24% of 2798 women, respectively. Women with SBI had increased odds of perinatal death [adjusted odd ratio (AOR): 1.50] and neonatal death (AOR: 1.47) as compared to women with optimal birth intervals, while women with LBI had slightly lower odds of perinatal deaths (AOR: 0.96), but increased odds of neonatal deaths (AOR: 1.12). Further, the pregnancies with both SBI and LBI were associated with increased odds of short body length, low birth weight, small head circumference and low APGAR score.

CONCLUSION

Nearly half of all pregnancies do not have optimal birth spacing albeit there is wide heterogeneity in the distribution of BI in various Pakistani ethnicities. Pregnancies with SBI and LBI had high risk of adverse reproductive outcome. Intervention programs for maternal and child health need to emphasize optimal birth spacing.

Fertility Intention Among Chinese Reproductive Couples During the COVID-19 Outbreak: A Cross-Sectional Study

A decline in the fertility rate has been observed worldwide, which hampers social development severely. Given the impacts of COVID-19 on individuals and society, it is of great significance to investigate the fertility intention of reproductive couples under COVID-19. The convenience sampling method was used to obtain our study sample. The self-administered questionnaire included the following components: sociodemographic characteristics (age, residence, education, occupation, characteristics of the couples, and annual household income), reproductive history (parity, number of children, child gender, and duration of preparing pregnancy), and attitudes toward COVID-19, was distributed online via an applet of WeChat. The results showed that among 4,133 valid questionnaires, 1,091 had fertility intention before COVID-19, whereas 3,042 did not, indicating a fertility intention rate of 26.4% among participating couples. Of the 1,091 couples who had fertility intention before COVID-19, 520 (47.7%) were affected by the outbreak, whereas 571 (52.3%) were not. By multivariable logistic regression analysis, we further found that couples living in Hubei Province, the epicenter in China (OR 2.20, 95% CI 1.35–3.60), and couples who prepared for pregnancy longer before COVID-19 (OR 1.19, 95% CI 1.06–1.33) were more likely to change their fertility intention under the pandemic. In addition, most of the participants reported their fertility intention was affected by the inconvenience of seeking medical service under COVID-19. Therefore, more forms of medical services to provide convenience for patients might be effective ways to reverse the declined fertility intention rate in facing COVID-19.

Impact of Medicaid Expansion on Interpregnancy Interval

OBJECTIVES

Medicaid expansion under the Affordable Care Act (ACA) improved access to reproductive health care for low-income women and birthing people who were previously ineligible for Medicaid. We aimed to evaluate if the expansion affected the risk of having a short interpregnancy interval (IPI), a preventable risk factor for adverse pregnancy outcomes.

METHODS

We evaluated parous singleton births to mothers aged 19 or older from U.S. birth certificate data 2009-2018. We estimated the effect of residing in a state that expanded Medicaid access (expansion status determined at 60 days after the prior live birth) on the risk of having a short IPI (<12 months) using difference-in-differences (DID) methods in linear probability models. We stratified the analyses by maternal characteristics and county-level reproductive health care access.

RESULTS

Overall risk of short IPI was 14.9% in expansion states and 16.3% in non-expansion states. The expansion was not associated with a significant change in risk of having a short IPI (adjusted mean percentage point change 1.24 [-1.64, 4.12]). Stratified results also did not provide support for an association.

CONCLUSIONS

ACA Medicaid expansion did not have an impact on risk of short IPI. Preventing short IPI may require more comprehensive policy interventions in addition to health care access.

The confounder matrix: A tool to assess confounding bias in systematic reviews of observational studies of etiology

Systematic reviews and meta-analyses are essential for drawing conclusions regarding etiologic associations between exposures or interventions and health outcomes. Observational studies comprise a substantive source of the evidence base. One major threat to their validity is residual confounding, which may occur when component studies adjust for different sets of confounders, fail to control for important confounders, or have classification errors resulting in only partial control of measured confounders. We present the confounder matrix-an approach for defining and summarizing adequate confounding control in systematic reviews of observational studies and incorporating this assessment into meta-analyses. First, an expert group reaches consensus regarding the core confounders that should be controlled and the best available method for their measurement. Second, a matrix graphically depicts how each component study accounted for each confounder. Third, the assessment of control adequacy informs quantitative synthesis. We illustrate the approach with studies of the association between short interpregnancy intervals and preterm birth. Our findings suggest that uncontrolled confounding, notably by reproductive history and sociodemographics, resulted in exaggerated estimates. Moreover, no studies adequately controlled for all core confounders, so we suspect residual confounding is present, even among studies with better control. The confounder matrix serves as an extension of previously published methodological guidance for observational research synthesis, enabling transparent reporting of confounding control and directly informing meta-analysis so that conclusions are drawn from the best available evidence. Widespread application could raise awareness about gaps across a body of work and allow for more valid inference with respect to confounder control.

Short interpregnancy interval and pregnancy outcomes: How important is the timing of confounding variable ascertainment?

BACKGROUND

Estimation of causal effects of short interpregnancy interval on pregnancy outcomes may be confounded by time-varying factors. These confounders should be ascertained at or before delivery of the first ("index") pregnancy, but are often only measured at the subsequent pregnancy.

OBJECTIVES

To quantify bias induced by adjusting for time-varying confounders ascertained at the subsequent (rather than the index) pregnancy in estimated effects of short interpregnancy interval on pregnancy outcomes.

METHODS

We analysed linked records for births in British Columbia, Canada, 2004-2014, to women with ≥2 singleton pregnancies (n = 121 151). We used log binomial regression to compare short (<6, 6-11, 12-17 months) to 18-23-month reference intervals for 5 outcomes: perinatal mortality (stillbirth and neonatal death); small for gestational age (SGA) birth and preterm delivery (all, early, spontaneous). We calculated per cent differences between adjusted risk ratios (aRR) from two models with maternal age, low socio-economic status, body mass index, and smoking ascertained in the index pregnancy and the subsequent pregnancy. We considered relative per cent differences <5% minimal, 5%-9% modest, and ≥10% substantial.

RESULTS

Adjustment for confounders measured at the subsequent pregnancy introduced modest bias towards the null for perinatal mortality aRRs for <6-month interpregnancy intervals [-9.7%, 95% confidence interval [CI] -15.3, -6.2). SGA aRRs were minimally biased towards the null (-1.1%, 95% CI -2.6, 0.8) for <6-month intervals. While early preterm delivery aRRs were substantially biased towards the null (-10.4%, 95% CI -14.0, -6.6) for <6-month interpregnancy intervals, bias was minimal for <6-month intervals for all preterm deliveries (-0.6%, 95% CI -2.0, 0.8) and spontaneous preterm deliveries (-1.3%, 95% CI -3.1, 0.1). For all outcomes, bias was attenuated and minimal for 6-11-month and 12-17-month interpregnancy intervals.

CONCLUSION

These findings suggest that maternally linked pregnancy data may not be needed for appropriate confounder adjustment when studying the effects of short interpregnancy interval on pregnancy outcomes.

Increased Risk of ADHD at Short and Long Interpregnancy Intervals in a National Birth Cohort

BACKGROUND

Short or long interpregnancy interval (IPI) may adversely impact conditions for foetal development. Whether attention deficit hyperactivity disorder (ADHD) is related to IPI has been largely unexplored.

OBJECTIVES

To examine the association between IPI and ADHD in a large, population-based Finnish study.

METHODS

All children born in Finland between 1991 and 2005 and diagnosed with ADHD (ICD-9 314x or ICD-10 F90.x) from 1995 to 2011 were identified using data from linked national registers. Each subject with ADHD was matched to 4 controls based on sex, date of birth, and place of birth. A total of 9564 subjects with ADHD and 34,479 matched controls were included in analyses. IPI was calculated as the time interval between sibling birth dates minus the gestational age of the second sibling. The association between IPI and ADHD was determined using conditional logistic regression and adjusted for potential confounders.

RESULTS

Relative to births with an IPI of 24 to 59 months, those with the shortest IPI (<6 months) had an increased risk of ADHD (odds ratio [OR] 1.30, 95% confidence interval (CI) 1.12, 1.51) and the ORs for the longer IPI births (60-119 months and ≥120 months) were 1.12 (95% CI 1.02, 1.24) and 1.25 (95% CI 1.08, 1.45), respectively. The association of longer IPI with ADHD was attenuated by adjustment for maternal age at the preceding birth, and comorbid autism spectrum disorders did not explain the associations with ADHD.

CONCLUSIONS

The risk of ADHD is higher among children born following short or long IPIs although further studies are needed to explain this association.

Postpartum contraception method type and risk of a short interpregnancy interval in a state Medicaid population

OBJECTIVE

To evaluate the likelihood of a short interpregnancy interval (IPI) resulting in a birth among women covered by Medicaid, as a function of postpartum contraceptive method type.

STUDY DESIGN

We used Medicaid claims and eligibility data to identify women (aged 15-44) who had a Medicaid-financed birth in Delaware in the years 2012-2014 (n = 10,328). Claims were analyzed to determine postpartum contraceptive type within 60 days of the index birth, and linked birth certificates were used to determine the incidence and timing of a subsequent birth through 2018 (regardless of payer). We used logistic regression to analyze the likelihood of having a short IPI following the index birth as a function of postpartum contraceptive type, controlling for preterm births, parity, having a postpartum checkup, and maternal characteristics including age, race, education, and marital status.

RESULTS

Compared to patients receiving postpartum long-acting reversible contraceptive methods (LARC), patients with no contraceptive claims had nearly 5 times higher odds (odds ratio [OR] = 4.98, confidence interval [CI] = 3.05-8.13) and those with claims for moderately effective methods (injectable, pill, patch, or ring) had 3.5 times higher odds (OR = 3.51, CI = 2.13-5.77) of a subsequent birth following a short IPI.

CONCLUSIONS

In a state population of Medicaid-enrolled women, women with claims for postpartum LARC had substantially lower risk of a short IPI resulting in a birth.

IMPLICATIONS

Women who received LARC within 60 days postpartum are less likely to experience a short interpregnancy interval resulting in a birth. The evidence suggests that recent state policy changes that make postpartum LARC more accessible to those that desire it will be an effective strategy in helping patients obtain desired birth intervals.

Intentionally or Ambivalently Risking a Short Interpregnancy Interval: Reproductive-Readiness Factors in Women's Postpartum Non-Use of Contraception

A focus of research on short interpregnancy intervals (IPI) has been on young disadvantaged women whose births are likely to be unintended. Later initiation of family formation in the United States and other high-income countries points to the need to also consider a woman's attributes indicative of readiness for purposefully accelerated family formation achieved through short IPIs. We test for whether factors indicating "reproductive readiness"-including being married, being older, and having just had a first birth or a birth later than desired-predict a woman's non-use of contraception in the postpartum months. We also test for whether this contraceptive non-use results explicitly from wanting to become pregnant again. The data come from the 2012-2015 Pregnancy Risk Assessment Monitoring System, representing women who recently gave birth in any of 35 U.S. states and New York City (N = 120,111). We find that these reproductive-readiness factors are highly predictive of women's postpartum non-use of contraception because of a stated desire to become pregnant and are moderately predictive of contraceptive non-use without an explicit pregnancy intention. We conclude that planning for, or ambivalently risking, a short IPI is a frequent family-formation strategy for women whose family formation has been delayed. This is likely to become increasingly common as family formation in the United States is initiated later in the reproductive life course.

Prenatal Depression and Risk of Short Interpregnancy Interval in a Predominantly Puerto Rican Population

Background: Short interpregnancy interval (IPI) is associated with risk of adverse pregnancy outcomes; however, few studies have evaluated the role of depression as a risk factor for short IPI. Puerto Rican women in the United States experience disparities in adverse birth outcomes and have the highest birth rates. Methods: We analyzed the association between prenatal depressive symptoms and IPI in Proyecto Buena Salud, a prospective cohort of predominantly Puerto Rican women in Western Massachusetts (2006-2011). Depression was measured using the Edinburgh Postnatal Depression Scale (EPDS) in early, mid, and late pregnancy. We calculated follow-up time as the difference between the date of delivery of the index pregnancy and the last menstrual period of the subsequent pregnancy using medical records and billing data. We defined short IPI as ≤18 months. Results: Of 1262 eligible women, 35% (n = 440) had at least probable minor depression (EPDS scores ≥13) and 25% (n = 315) had probable major depression (EPDS scores ≥15). Participants were followed for a median of 3.7 years (interquartile range = 1.4-6.0 years) and 240 (20.6%) participants experienced a short IPI. After adjusting for risk factors, women with probable minor depression (adjusted odds ratio [aOR] = 1.39, 95% confidence interval [CI] = 1.02-1.88) and probable major depression (aOR = 1.42, 95% CI = 1.02-1.97) during pregnancy had increased odds of short IPI. Conclusions: Prenatal depressive symptoms were common in this Puerto Rican population and were associated with a modest increase in odds of short IPI. Further examination of the pathways through which mental health may affect IPI in vulnerable populations is warranted.

Patterns and determinants of short and long birth intervals among women in selected sub-Saharan African countries

Optimal birth spacing (defined as a birth spacing of 24-59 months) is incontrovertibly linked to better health outcomes for both mothers and babies. Using the most recent available Demographic and Health Survey data, we examined the patterns and determinants of short and long birth intervals among women in selected sub-Saharan African (SSA) countries.Reproductive health and sociodemographic data of 98,934 women from 8 SSA countries were analyzed. Unadjusted and adjusted multinomial logistic regression models were used to examine the net relationship between all the independent variables and short and long birth intervals.Overall, the majority of women in all the countries optimally spaced births. However, a significant proportion of women had short birth intervals in Chad (30.2%) and the Democratic Republic of Congo (Congo DRC) (27.1%). Long birth spacing was more common in Eastern and Southern African countries, with Zimbabwe having the highest rate of long term birth interval (27.0%). Women who were aged 35 years and above in Uganda (RRR = 0.72, CI = 0.60-0.87), Tanzania (RRR = 0.62, CI = 0.49-0.77), Zimbabwe (RRR = 0.52, CI = 0.31-0.85), Nigeria (RRR = 0.82, CI = 0.72-0.94) and Togo (RRR = 0.67, CI = 0.46-0.96) had significantly lower odds of having short birth intervals compared to women aged 15-24 years. Older women (above 34 years) had increased odds for long birth intervals in all countries studied (Chad (RRR = 1.44, CI = 1.18-1.76), Congo DRC (RRR = 1.73, CI = 1.33-2.15), Malawi (RRR = 1.54, CI = 1.23-1.94) Zimbabwe (RRR = 1.95, CI = 1.26-3.02), Nigeria (RRR = 1.85 CI = 1.56-2.20), Togo (RRR = 2.12, CI = 1.46-3.07), Uganda (RRR = 1.48, CI = 1.15-1.91), Tanzania RRR = 2.12, CI = 1.53-2.93).The analysis suggested that the determinants of long and birth intervals differ and varies from country to country. The pattern of birth spacing found in this study appears to mirror the contraceptive use and fertility rate in the selected SSA countries. Birth intervals intervention addressing short birth intervals should target younger women in SSA, especially in Chad and Congo DRC, while intervention for long birth spacing should prioritize older, educated and wealthy women.

Fertility intentions and the way they change following birth- a prospective longitudinal study

BACKGROUND

Women's fertility intentions, their desired number of children and desired inter-pregnancy interval (IPI) are related to micro (personal) and macro (socio-cultural) level factors. We investigated factors that contribute to changes in women's fertility intentions in Israel, a developed country with high birth rates.

METHODS

Pregnant women (N = 1163), recruited from prenatal clinics and hospitals in two major metropolitan areas, completed self-report questionnaires prenatally (≥24 weeks gestation) and postpartum (2 months after childbirth). Women reported their socio-demographic background and obstetric history prenatally, their desired number of children and IPI at both time-points, and their objective and subjective birth experiences postpartum.

RESULTS

The findings indicated that background characteristics were related to prenatal fertility intentions. The strongest contributor to prenatal fertility intentions was women's degree of religiosity- the more religious they were, the more children they desired and the shorter their intended IPI. Women's postpartum fertility intentions were mostly consistent with their prenatal reports. In regression models, women who were very-religious, more educated and had previously given birth were less likely to report a lower number of desired of children at postpartum, compared to their prenatal report. Women who reported greater birth satisfaction and gave birth for the first time were less likely to change desired IPI.

CONCLUSION

Having a negative birth experience could adversely affect women's fertility intentions. Yet, in a pronatalist and medicalized birth culture, social pressures may decrease the effects of birth experiences on fertility intentions.

Overview and Introduction to Autism Spectrum Disorder (ASD)

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder generally manifesting in the first few years of life and tending to persist into adolescence and adulthood. It is characterized by deficits in communication and social interaction and restricted, repetitive patterns of behavior, interests, and activities. It is a disorder with multifactorial etiology. In this chapter, we will focus on the most important and common epidemiological studies, pathogenesis, screening, and diagnostic tools along with an explication of genetic testing in ASD.

Examining internal migration effects on short versus long interbirth intervals in Cotonou, Benin Republic

Background

The literature on migration-fertility relationship uses various measures of fertility, such as fertility rates, actual fertility and family size preferences. This study introduces a different measure—interbirth intervals over women’s reproductive years—to examine how internal migration is associated with short interbirth intervals (less than 24 months) and long interbirth intervals (greater than 60 months) in Cotonou, the largest city of Benin Republic.

Methods

The paper uses primary data on 2852 live births to 1659 women aged 15–49 years from the 2018 Fertility and Migration Survey in Cotonou. Competing-risks models were fitted for the analysis.

Results

Nineteen percent of live births were of short interbirth intervals and 16% were of long interbirth intervals. The prevalence of short interbirth intervals was higher among migrants who spent less than 5 years in Cotonou (29%) than among non-migrants (19%) and earlier migrants (18%). Non-migrants had the highest proportion of long interbirth intervals (19%). Within the first 5 years following the migration to Cotonou, migrants had higher subhazard ratio (SHR) of short interbirth intervals (SHR: 1.71, 95% CI: 1.33–2.21) and lower SHR of long interbirth intervals (SHR: 0.64, 95% CI: 0.47–0.87) than non-migrants. This association holds after controlling for socioeconomic characteristics—but with a slightly reduced gap between migrants who spent less than 5 years in Cotonou and non-migrants. Afterwards and irrespective of women’s socioeconomic backgrounds, migrants who spent 5 or more years in Cotonou and non-migrants had similar risks of short and long interbirth intervals. Finally, from 5 years of stay in Cotonou, migrants for reasons other than school or job were less likely to experience short interbirth intervals (SHR: 0.65, 95% CI: 0.46–0.98 for migrants who spent 5–10 years in Cotonou, and SHR: 0.74, 95% CI: 0.54–1.02 for migrants who spent more than 10 years in Cotonou) than non-migrants.

Conclusion

Family planning programmes should mainly target migrants in the early years after their arrival in Cotonou. Moreover, non-migrants need to be sensitised on the adverse health outcomes of long interbirth intervals.

Interpregnancy interval and risk of stillbirth: a population-based case control study

PURPOSE

We examined the association between interpregnancy intervals (IPIs) and stillbirth (defined as fetal death ≥20 weeks), as both short and long IPIs have been associated with adverse perinatal outcomes. Prior pregnancy loss is also a known risk factor for stillbirth, and women who suffer a prior loss often have shorter IPIs. For these reasons, we also sought to quantify the proportion of the association between prior pregnancy loss and subsequent stillbirth risk that may be attributed to a short IPI.

METHODS

We used data from the Stillbirth Collaborative Research Network, a multisite case-control study conducted in 2006-2008, restricted to singleton pregnancies among multiparous or multigravid women (985 controls and 291 cases). We accounted for complex sample design and nonparticipation with weighted multivariable logistic regression.

RESULTS

In the adjusted models, IPIs <6 months, as compared with a reference of 18-23 months, were associated with increased odds of stillbirth (aOR 1.6, 95% CI: 0.8, 3.4). Long IPIs (60-100 months) were also associated with an increased odds of stillbirth (aOR 2.4, 95% CI: 1.2, 4.5). After control for covariates, about one-fifth (21.2%) of the association of prior pregnancy loss (stillbirth, ectopic pregnancy, molar pregnancy, or spontaneous abortion) and stillbirth may be attributable to a short IPI.

CONCLUSIONS

Our results suggest that women who experience a prior pregnancy loss may benefit from additional counseling on adequate birth spacing to reduce subsequent stillbirth risk.

The contribution of environmental exposure to the etiology of autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition of heterogeneous etiology. While it is widely recognized that genetic and environmental factors and their interactions contribute to autism phenotypes, their precise causal mechanisms remain poorly understood. This article reviews our current understanding of environmental risk factors of ASD and their presumed adverse physiological mechanisms. It comprehensively maps the significance of parental age, teratogenic compounds, perinatal risks, medication, smoking and alcohol use, nutrition, vaccination, toxic exposures, as well as the role of extreme psychosocial factors. Further, we consider the role of potential protective factors such as folate and fatty acid intake. Evidence indicates an increased offspring vulnerability to ASD through advanced maternal and paternal age, valproate intake, toxic chemical exposure, maternal diabetes, enhanced steroidogenic activity, immune activation, and possibly altered zinc-copper cycles and treatment with selective serotonin reuptake inhibitors. Epidemiological studies demonstrate no evidence for vaccination posing an autism risk. It is concluded that future research needs to consider categorical autism, broader autism phenotypes, as well as autistic traits, and examine more homogenous autism variants by subgroup stratification. Our understanding of autism etiology could be advanced by research aimed at disentangling the causal and non-causal environmental effects, both founding and moderating, and gene-environment interplay using twin studies, longitudinal and experimental designs. The specificity of many environmental risks for ASD remains unknown and control of multiple confounders has been limited. Further understanding of the critical windows of neurodevelopmental vulnerability and investigating the fit of multiple hit and cumulative risk models are likely promising approaches in enhancing the understanding of role of environmental factors in the etiology of ASD.

Effects of birth spacing on adverse childhood health outcomes: evidence from 34 countries in sub-Saharan Africa

Background: Interpregnancy intervals (IPI) are independently associated with maternal, perinatal, infant and child outcomes. Birth spacing is a recommended tool to reduce adverse health outcomes especially among children. This study aims to determine the prevalence of adverse child health outcomes in sub-Saharan Africa (SSA) countries and to examine the association between the length of preceding birth interval child health outcomes.Methods: Secondary data from Demographic and Health Survey (DHS) in 34 SSA countries with 299 065 births was used in this study. The outcome variables were infant mortality, low birth weight, stunting, underweight, wasting, overweight and anemia. Percentage was used in univariate analysis. Cox proportional hazard regression was used to examine association between the adjusted model of preceding birth interval and infant mortality. Multinomial and binary logistic regression models were used to examine the association between under-five children adverse health outcomes and interpregnancy birth interval.Results: Infant mortality was lowest in Gambia (3.4%) and highest in Sierra Leone (9.3%). Comoros (16.8%) accounted for the highest percentage of low birth weight (<2.5 kg). Child stunting was as high as 54.6% in Burundi. IPIs of <24 months, 24-36 months, 37-59 months and ≤60 months accounted for 19.3, 37.8, 29.5 and 13.4% respectively. Median IPI was 34 months. Results from Cox proportional hazard regression showed that children with preceding birth interval <24 months had 57% higher risk of infant mortality, compared to children with IPI of 24-36 months (Hazard ratio (HR) = 1.57; 95%CI: 1.45, 1.69). However, there were 19% and 10% reduction in the risk of infant mortality at IPIs of 37-59 months and ≥60 months, compared to 24-36 months IPI (37-59 months: HR = 0.81; 95%CI: 0.75, 0.87; ≥60 months: HR = 0.90; 95%CI: 0.81, 0.99).Conclusion: The findings of this study suggest the need for urgent intervention to promote the recommended interpregnancy interval of 24-36 months to reduce adverse child health outcomes. These data also bring into limelight the importance of exclusive breastfeeding to enhance proper nutritional approach and to prolong lactational amenorrhea. Health care system stakeholders would find this study interesting as a base for policy formulation and implementation.

Association of Short Interpregnancy Interval With Pregnancy Outcomes According to Maternal Age

IMPORTANCE

Interpregnancy intervals shorter than 18 months are associated with higher risks of adverse pregnancy outcomes. It is currently unknown whether short intervals are associated with increased risks among older women to the same extent as among younger women.

OBJECTIVE

To evaluate whether the association between short interpregnancy (delivery to conception) interval and adverse pregnancy outcomes is modified by maternal age.

DESIGN, SETTING, AND PARTICIPANTS

A population-based cohort study conducted in British Columbia, Canada, evaluated women with 2 or more singleton pregnancies from 2004 to 2014 with the first (index) pregnancy resulting in a live birth. Data analysis was performed from January 1 to July 20, 2018.

MAIN OUTCOMES AND MEASURES

Risks of maternal mortality or severe morbidity (eg, mechanical ventilation, blood transfusion >3 U, intensive care unit admission, organ failure, death), small-for-gestational age (<10th birthweight percentile for gestational age and sex), fetal and infant composite outcome (stillbirth, infant death, <third birthweight percentile for gestational age and sex, delivery <28 weeks), and spontaneous and indicated preterm delivery. Risks of each outcome for 3- to 24-month interpregnancy intervals were estimated, according to maternal age at index birth (20-34 and ≥35 years). Adjusted risk ratios (aRRs) comparing predicted risks at 3-, 6-, 9-, and 12-month intervals with risks at 18-month intervals for each age group were calculated. The potential role of other factors explaining any differences (unmeasured confounding) was examined in several sensitivity analyses.

RESULTS

Among 148 544 pregnancies, maternal mortality or severe morbidity risks were increased at 6-month compared with 18-month interpregnancy intervals for women aged 35 years or older (0.62% at 6 months vs 0.26% at 18 months; aRR, 2.39; 95% CI, 2.03-2.80), but not for women aged 20 to 34 years (0.23% at 6 months vs 0.25% at 18 months; aRR, 0.92; 95% CI, 0.83-1.02). Increased adverse fetal and infant outcome risks were more pronounced for women aged 20 to 34 years (2.0% at 6 months vs 1.4% at 18 months; aRR, 1.42; 95% CI, 1.36-1.47) than women 35 years or older (2.1% at 6 months vs 1.8% at 18 months; aRR, 1.15; 95% CI, 1.01-1.31). Risks of spontaneous preterm delivery at 6-month interpregnancy intervals were increased for women 20 to 34 years old (5.3% at 6 months vs 3.2% at 18 months; aRR, 1.65; 95% CI, 1.62-1.68) and to a lesser extent for women 35 years or older (5.0% at 6 months vs 3.6% at 18 months; aRR, 1.40; 95% CI, 1.31-1.49). Modest increases in risks of small-for-gestational age and indicated preterm delivery at short intervals did not vary meaningfully by maternal age. Sensitivity analyses suggested that observed associations were not fully explained by unmeasured confounding.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that short interpregnancy intervals are associated with increased risks for adverse pregnancy outcomes for women of all ages.

Interpregnancy Intervals in a Contemporary Manitoba Cohort: Prevalence of So-Called Suboptimal Intervals and Associated Maternal Characteristics

OBJECTIVE

Short and long interpregnancy intervals (IPIs) have been associated with various adverse outcomes, and a 2016 American College of Obstetricians and Gynecologists' Committee Opinion recommends an optimal IPI of 18 months to 5 years. Descriptive data on the IPI in Canada are lacking. The objective of this study was to examine IPIs in a Manitoba cohort.

METHODS

The study analyzed a subset of records from a larger dataset used to examine the IPI and adverse perinatal outcomes. For that study, Manitoba's Hospital Abstracts data were searched to identify births from 1985 to 2014. Each two consecutive live births to the same mother formed a sibling pair. The IPI was calculated as the interval between the two siblings' births, minus the younger sibling's GA. Information on maternal characteristics was extracted from various datasets housed in the Manitoba Population Research Data Repository. The current analysis examined second and higher-order births between 2010 and 2014. The proportion of suboptimal IPIs was determined and IPIs were cross-tabulated with birth year and maternal subgroups.

RESULTS

More than half of pregnancies were conceived following a suboptimal interval. IPIs of less than 6 months - which have been associated with the highest risk of adverse outcomes - were more prevalent among certain subgroups. These included younger women as well as women who received inadequate prenatal care, smoked or drank alcohol during pregnancy, were low income, or did not graduate from high school.

CONCLUSION

Suboptimal IPIs were common in this Manitoba cohort. Stakeholders should consider whether greater efforts to promote appropriate birth spacing are warranted.

The Role of Extremes in Interpregnancy Interval in Women at Increased Risk for Adverse Obstetric Outcomes Due to Health Disparities: A Literature Review

Background:

The interpregnancy interval (IPI) defines the time between two consecutive gestations. In the general population, women with IPIs that fall outside the recommended 18-24 month range appear to be at modestly increased risk for adverse obstetric outcomes.

Objective:

The aim of this review was to assess the impact of extremes in IPI in populations with an increased baseline risk for adverse obstetric outcomes due to disparities in health and health care, including racial and ethnic groups, adolescents, and those of lower socioeconomic status.

Methods:

We conducted a MEDLINE/Pubmed literature search in February 2016. Identified articles were reviewed and assigned a level of evidence.

Results:

The 24 studies included in our final review were mainly retrospective with considerable heterogeneity in definitions and outcomes that prevented a quantitative meta-analysis.

Conclusion:

The results of our review suggest that at-risk populations may have an increased frequency of shortened IPIs though the impact appears to be moderate and inconsistent. There was insufficient evidence to draw meaningful conclusions regarding a prolonged IPI or the effect of interventions. Based on the current literature, under-served populations are more likely to have a shortened IPI which increased the incidence of prematurity and low birth weight in some groups though the effect on additional obstetric outcomes is difficult to assess

Factors associated with pregnancy intention among women who have experienced a short birth interval: findings from the 2009 to 2011 Mississippi and 2009 Tennessee Pregnancy Risk Assessment Monitoring System

PURPOSE

One-third of all pregnancies in the United States are conceived within 18 months of a prior live birth. Preventing unintended pregnancies may help to decrease the prevalence of pregnancies with these short interpregnancy intervals. However, data on factors associated with pregnancy intention among women who have had short birth intervals are sparse. Pregnancy Risk Assessment Monitoring System data were used to further evaluate these associations.

METHODS

Because only Mississippi and Tennessee Pregnancy Risk Assessment Monitoring System include a survey question about birth interval length, this analysis was limited to women from those states who recently had a short birth interval (n = 384). Pregnancy intention and demographic, lifestyle, and reproductive data were obtained from surveys and birth certificates. Logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Nearly 76% of women with short birth intervals reported their pregnancy as unintended. Women who were non-Hispanic black or consumed alcohol during pregnancy had statistically significant increased odds of reporting the pregnancy with a short birth interval as being unintended (OR = 3.98; 95% CI: 1.73-9.16 and OR = 10.56; 95% CI: 1.80-61.83, respectively).

CONCLUSIONS

Although all women should be counseled on postpartum contraceptive use, findings suggest that important subpopulations of women may benefit from more targeted counseling during prenatal care visits and the immediate postpartum hospital stay regarding the importance of using contraception to not only better space pregnancies but also prevent unintended pregnancies.

Association between maternal interpregnancy interval after live birth or pregnancy termination and birth weight: a quantile regression analysis

We used quantile regression (QR) to assess if the length of the interpregnancy interval (IPI) after live birth and pregnancy termination is associated with weight in subsequent birth. The analysis included 9663 and 3400 women with IPI after live birth and pregnancy termination, respectively. For the women after live birth, an IPI < 12 months had negative effects at the 5th and 10th quantiles of the birth weight (BW) distribution. When the BW was beyond the 90th quantile, the BWs of newborns whose mothers with longer IPI (36-59 months) were higher than the reference group (18~23 months). For women after pregnancy termination in the 10^th quantile, it was observed that those pregnant women with IPIs between 36 and 47 months had a negative effect (150 g) on BW compared with the reference group. This finding revealed that mothers with IPI < 12 months resulted in a decrease of 85 g at 75th quantile. The impact of IPI > 119 months in the upper quantile (95^th) had an increase of 330 g in BW. Our results demonstrated that both short (<12 months) and long (>36 months) IPIs are independently associated with higher risks of low birth weight (LBW) and macrosomia.

The Impact of Computing Interpregnancy Intervals Without Accounting for Intervening Pregnancy Events

BACKGROUND

Short interpregnancy intervals (IPI) are associated with poor birth outcomes. Often, only livebirths are considered to estimate IPI. The objective of our work is to explore whether the associations between demographic, behavioural, and pregnancy variables and IPI change when events other than livebirth are included.

METHODS

We used data from the 2006-10 and 2011-13 period of the National Survey of Family Growth (NSFG). We defined IPI using the conception date of the index pregnancy and the event date of the previous one ending in (i) livebirth; (ii) stillbirth; (iii) miscarriage; (iv) abortion; or (v) any of these events. Risk ratios (RR) were estimated for short IPI (<18 months), and demographic, pregnancy, and behavioural variables using log-linear models.

RESULTS

When intervening events are included, the association between short IPI and its predictors vary by definition, especially for unintended versus intended pregnancies (only livebirth risk ratio [RR] 1.34, 95% confidence interval [CI] 1.2, 1.5) versus livebirth and miscarriage RR 1.14, 95% CI 1.0, 1.3) and women older than 30 vs. younger than 20 at resolution of the previous pregnancy (only livebirth RR 1.22, 95% CI 1.0, 1.5 versus livebirth and miscarriage RR 1.36, 95% CI 1.2, 1.6).

CONCLUSIONS

Including miscarriage as an intervening event in the calculation of IPI changes the association between several risk factors and short IPI. However, the association between short IPI and preterm birth does not vary when different IPI calculations are used.

Interpregnancy Interval and Congenital Anomalies: A Record-Linkage Study Using the Manitoba Population Research Data Repository

OBJECTIVE

Congenital anomalies are a serious public health issue, and relatively few modifiable risk factors have been identified. Our objective was to investigate one such potential risk factor, the interpregnancy interval (IPI).

METHODS

We conducted a secondary analysis of data housed at the Manitoba Centre for Health Policy. In-hospital live births and stillbirths of at least 20 weeks' gestation were identified, and consecutive births to the same mother were grouped into sibling pairs to calculate the IPI for the younger siblings of each pair. Logistic regression models were fit to examine the association between the IPI and any congenital anomaly, as well as CNS and chromosomal anomalies, while controlling for potentially confounding sociodemographic and clinical factors.

RESULTS

Among 172 909 live births and stillbirths, the IPI was not significantly associated with congenital anomalies overall or with chromosomal anomalies. Short IPIs were associated with significantly increased odds of CNS anomalies relative to IPIs of 18-23 months (adjusted OR [aOR] for IPIs <6 months 2.15; 95% CI 1.48-3.12), whereas the aOR for IPIs ≥60 months was elevated but not statistically significant (aOR 1.50; 95% CI 0.96-2.34). In a sensitivity analysis in which the cohort was restricted to births from 2003 onwards (which yielded more complete data on health-related behaviours), the observed effect for IPIs shorter than 6 months and CNS anomalies was attenuated and no longer significant, but it remained elevated (aOR 1.65; 95% CI 0.85-3.24).

CONCLUSION

The findings for CNS anomalies warrant further investigation.

Postpartum contraception: initiation and effectiveness in a large universal healthcare system

BACKGROUND

Repeat pregnancies after a short interpregnancy interval are common and are associated with negative maternal and infant health outcomes. Few studies have examined the relative effectiveness of postpartum contraceptive choices.

OBJECTIVE

We aimed to determine the initiation trends and relative effectiveness of postpartum contraceptive methods, with typical use, on prevention of short delivery intervals (≤27 months) among women with access to universal healthcare, including coverage that entails no co-payments and allows unlimited contraceptive method switching.

STUDY DESIGN

This retrospective cohort study included women who were enrolled in the United States military healthcare system who were admitted for childbirth between October 2010 and March 2015, with ≥6 months postpartum enrollment. With the use of insurance records, we determined the most effective contraceptive method initiated during the first 6 months after delivery, even if subsequently discontinued. Rates of interdelivery intervals of ≤27 months, as proxies for interpregnancy intervals ≤18 months, were determined with the use of the Kaplan-Meier estimator. Women who were disenrolled, who reached 27 months after delivery without another delivery, or who reached the end of the study period were censored. The influence of sociodemographic variables and contraceptive choices on time to subsequent delivery was evaluated by Cox regression analysis, which accounted for a possible correlation among multiple deliveries by an individual woman.

RESULTS

During the study timeframe, 373,840 women experienced a total of 450,875 postpartum intervals. Women averaged 27 (standard deviation, 5.3) years of age at the time of delivery; 33.9% of them were <25 years old; 15.5% of them were active duty service members, and 31.6% of them had insurance sponsors of junior enlisted rank (which suggests lower income). Postpartum contraceptive methods that were initiated included self or partner sterilization (7%), intrauterine device (13.5%), etonogestrel implant (3.4%), depot medroxyprogesterone acetate (2.5%), and pill, patch, or ring (36.8%). Furthermore, 36.7% of them did not initiate a prescription method. Etonogestrel implant initiation increased from 1.7% of postpartum women in the first year of our study to 5.3% in the final year. The estimated short interdelivery interval rate was 17.4%, but rates varied with contraceptive method: 1% with sterilization, 6% with long-acting reversible contraception, 12% with depot medroxyprogesterone, 21% with pill, patch, or ring, and 23% with no prescription method. In a multivariable analysis, the adjusted hazard of a short interdelivery interval was highest among women who were younger, on active duty, or with officer insurance sponsors. Compared with nonuse of any prescription contraceptive, the use of an intrauterine device reduced the hazard of a subsequent delivery (adjusted hazard ratio, 0.19; 95% confidence interval, 0.18-0.20), as did etonogestrel implant (adjusted hazard ratio, 0.21; 95% confidence interval, 0.19-0.23); the pill, patch, or ring had less effect (adjusted hazard ratio, 0.80; 95% confidence interval, 0.78-0.81).

CONCLUSION

Postpartum initiation of long-acting reversible contraception is highly effective at the prevention of short interdelivery intervals, whereas pill, patch, or ring methods are associated with rates of short interdelivery intervals similar to users of no prescription contraception. This study supports long-acting reversible contraception as first-line recommendations for postpartum women who wish to retain fertility but avoid early repeat pregnancy.

Short Interpregnancy Intervals: Results from the First Baby Study

BACKGROUND

Short interpregnancy interval (SIPI), defined as 18 months or fewer between delivery and subsequent conception, has become an independent marker of maternal and child health.

METHODS

We performed a secondary analysis of 18 months of data from The First Baby Study, a prospective cohort of women followed from pregnancy through 3 years after their first birth. Women with SIPIs by 6, 6 to 12, and 12 to 18 months were compared with those without conceptions at those times. We then analyzed pregnancy intention of the subpopulation of women with a SIPI of 18 months or fewer. Logistic regression analyses determined associations between maternal characteristics, including sociodemographic and reproductive indicators, and SIPI incidence and intention.

FINDINGS

Of 3,006 participants, 795 (26.5%) had a repeat pregnancy within 18 months: 58 (1.9%) occurred within 6 months, 242 (8.1%) between 6 and 12 months, and 495 (16.5%) between 12 and 18 months. Incidence of SIPI at each interval differed by maternal characteristics, including income, marital status, and intention. Most women (84%) with a SIPI of 6 months or less classified them as unintended. Less than 2% of women with SIPIs of 18 months or fewer reported any contraceptive use in the postpartum period and no pregnancies occurred with the use of very effective methods, including long-acting reversible contraception.

CONCLUSIONS

The population of women at risk for SIPI is not homogenous. Among those with SIPIs, there is a stark contrast in intention between those who conceive early (≤6 months) versus later (≥12 months). Given that almost no pregnancies occurred when women used postpartum contraception, contraceptive counseling and unfettered access should be available for those at greatest risk for an early, repeat, unintended pregnancy.

Interpregnancy Interval and Adverse Perinatal Outcomes: A Record-Linkage Study Using the Manitoba Population Research Data Repository

OBJECTIVE

To examine the association between the interpregnancy interval (IPI) and preterm birth, low birth weight, and SGA birth in a developed country with universal health coverage.

METHODS

We conducted a secondary analysis of data housed at the Manitoba Centre for Health Policy. All live births in Manitoba hospitals over a 29-year period were identified and consecutive births to the same mother were grouped into sibling pairs to calculate the IPI for the younger siblings. Logistic regression models were fit to examine the association between the IPI and adverse perinatal outcomes, adjusted for potentially confounding sociodemographic and clinical factors.

RESULTS

In a cohort of more than 171 000 births and relative to IPIs of 18 to 23 months, IPIs shorter than 12 and longer than 23 months were associated with significantly increased odds of preterm birth overall and both medically indicated and spontaneous preterm births, low birth weight, and SGA birth. The strongest association observed was for intervals shorter than 6 months and spontaneous preterm birth (adjusted OR 1.83, 95% CI 1.65-2.03). When the outcome was modelled as GA categories, the strongest association observed was for intervals shorter than 6 months and early preterm birth (<34 weeks' GA; adjusted OR 2.47, 95% CI 2.07-2.94).

CONCLUSION

If the associations observed between the IPI and adverse perinatal outcomes in this large, population-based cohort are causal, birth spacing could form an important target of public health messaging in Canada.

Birth Spacing and Risk of Autism and Other Neurodevelopmental Disabilities: A Systematic Review

CONTEXT

Both short and long interpregnancy intervals (IPIs) have recently been associated with increased risk of autism spectrum disorder (ASD). However, this association has not been systematically evaluated.

OBJECTIVE

To examine the relationship between birth spacing and the risk of ASD and other neurodevelopmental disabilities.

DATA SOURCES

Electronic databases from their inception to December 2015, bibliographies, and conference proceedings.

STUDY SELECTION

Observational studies with results adjusted for potential confounding factors that reported on the association between IPIs or birth intervals and neurodevelopmental disabilities.

DATA EXTRACTION

Two reviewers independently extracted data on study characteristics, IPIs/birth intervals, and outcome measures.

RESULTS

Seven studies (1 140 210 children) reported an association between short IPIs and increased risk of ASD, mainly the former subtype autistic disorder. Compared with children born to women with IPIs of ≥36 months, children born to women with IPIs of <12 months had a significantly increased risk of any ASD (pooled adjusted odds ratio [OR] 1.90, 95% confidence interval [CI] 1.16-3.09). This association was stronger for autistic disorder (pooled adjusted OR 2.62, 95% CI 1.53-4.50). Three of these studies also reported a significant association between long IPIs and increased risk of ASD. Short intervals were associated with a significantly increased risk of developmental delay (3 studies; 174 940 children) and cerebral palsy (2 studies; 19 419 children).

LIMITATIONS

Substantial heterogeneity, and few studies assessing neurodevelopmental disabilities other than ASD.

CONCLUSIONS

Short IPIs are associated with a significantly increased risk of ASD. Long IPIs also appear to increase the risk of ASD.