Birth Intervals and Health in Adulthood: A Comparison of Siblings Using Swedish Register Data

Birth Spacing and Parents' Physical and Mental Health: An Analysis Using Individual and Sibling Fixed Effects

An extensive literature has examined the relationship between birth spacing and subsequent health outcomes for parents, particularly for mothers. However, this research has drawn almost exclusively on observational research designs, and almost all studies have been limited to adjusting for observable factors that could confound the relationship between birth spacing and health outcomes. In this study, we use Norwegian register data to examine the relationship between birth spacing and the number of general practitioner consultations for mothers' and fathers' physical and mental health concerns immediately after childbirth (1-5 and 6-11 months after childbirth), in the medium term (5-6 years after childbearing), and in the long term (10-11 years after childbearing). To examine short-term health outcomes, we estimate individual fixed-effects models: we hold constant factors that could influence parents' birth spacing behavior and their health, comparing health outcomes after different births to the same parent. We apply sibling fixed effects in our analysis of medium- and long-term outcomes, holding constant mothers' and fathers' family backgrounds. The results from our analyses that do not apply individual or sibling fixed effects are consistent with much of the previous literature: shorter and longer birth intervals are associated with worse health outcomes than birth intervals of approximately 2-3 years. Estimates from individual fixed-effects models suggest that particularly short intervals have a modest negative effect on maternal mental health in the short term, with more ambiguous evidence that particularly short or long intervals might modestly influence short-, medium-, and long-term physical health outcomes. Overall, these results are consistent with small to negligible effects of birth spacing behavior on (non-pregnancy-related) parental health outcomes.

Does Early Childhood BCG Vaccination Improve Survival to Midlife in a Population With a Low Tuberculosis Prevalence? Quasi-experimental Evidence on Nonspecific Effects From 32 Swedish Birth Cohorts

The Bacillus Calmette-Guérin (BCG) vaccine for tuberculosis (TB) is widely used globally. Many high-income countries discontinued nationwide vaccination policies starting in the 1980s as the TB prevalence decreased. However, there is continued scientific interest in whether the general childhood immunity boost conferred by the BCG vaccination impacts adult health and mortality in low-TB contexts (known as nonspecific effects). While recent studies have found evidence of an association between BCG vaccination and survival to ages 34-45, it is unclear whether these associations are causal or driven by the unobserved characteristics of those who chose to voluntarily vaccinate. We use the abrupt discontinuation of mandatory BCG vaccination in Sweden in 1975 as a natural experiment to estimate the causal nonspecific effect of the BCG vaccine on cohort survival to midlife. Applying two complementary study designs, we find no evidence that survival to age 40 was affected by the discontinuation of childhood BCG vaccination. The results are consistent among both males and females and are robust to several sensitivity tests. Overall, despite prior correlational studies suggesting large nonspecific effects, we do not find any population-level evidence for a nonspecific effect of the BCG vaccine discontinuation on survival to age 40 in Sweden.

Birth Spacing and Health and Socioeconomic Outcomes Across the Life Course: Evidence From the Utah Population Database

The relationship between birth interval length and child outcomes has received increased attention in recent years, but few studies have examined offspring outcomes across the life course in North America. We use data from the Utah Population Database to examine the relationship between birth intervals and short- and long-term outcomes: preterm birth, low birth weight (LBW), infant mortality, college degree attainment, occupational status, and adult mortality. Using linear regression, linear probability models, and survival analysis, we compare results from models with and without sibling comparisons. Children born after a birth interval of 9-12 months have a higher probability of LBW, preterm birth, and infant mortality both with and without sibling comparisons; longer intervals are associated with a lower probability of these outcomes. Short intervals before the birth of the next youngest sibling are also associated with LBW, preterm birth, and infant mortality both with and without sibling comparisons. This pattern raises concerns that the sibling comparison models do not fully adjust for within-family factors predicting both spacing and perinatal outcomes. In sibling comparison analyses considering long-term outcomes, not even the very shortest birth intervals are negatively associated with educational or occupational outcomes or with long-term mortality. These findings suggest that extremely short birth intervals may increase the probability of poor perinatal outcomes but that any such disadvantages disappear over the extended life course.

Knowledge and Attitude Towards Short Birth Interval among Rural Women who Gave Birth in the Last Three Years at Dembecha District, Northwest Ethiopia, 2019

Background

A woman can have fewer children when intervals between consecutive births are optimal. This has great importance for the well-being of women, pregnancy outcomes, and the long-term health of children under the age of five. We can save 2millon of the 11 million deaths of children under the age of five per year by avoiding short birth intervals. It is affected by the knowledge and attitude of women, particularly rural women, who had a high fertility rate. To our deep review, this is the first study done in Ethiopia. Hence, this study aimed to assess knowledge and attitude towards short birth intervals and associated factors among rural women who gave birth in the last three years at Dembecha district, northwest Ethiopia.

Method

A community-based cross-sectional study was conducted from September 20 to October 20, 2019. A cluster sampling technique was employed to select the study participants and data were collected using a pre-tested, semi-structured, interviewer-administered questionnaire. Bivariable and multivariable logistic regression model was fitted to identify factors associated with knowledge and attitude towards short birth interval. The level of significant association was declared using the adjusted odds ratio (AOR) with 95% confidence interval (CI) and a p-value of <0.05.

Result

From the total study participants, 66.4% (95% CI: 63.0–70.0) had good knowledge and 45.9% (95% CI: 42.3–49.8) had a positive attitude towards short birth intervals. In multivariable logistic regression: marital status, antenatal care follow-up, maternal occupation, and wealth status were significantly associated with knowledge. In addition, antenatal care follow-up and maternal occupation were significantly associated with attitude.

Conclusion

Majority of the participants had poor knowledge and a positive attitude towards short birth intervals. Hence, interventions should be done to optimize women's knowledge and attitude towards short birth intervals by enhancing antenatal care utilization.

Interpregnancy Interval and Subsequent Severe Maternal Morbidity: A 16-Year Population-Based Study From California

Interpregnancy interval (IPI) is associated with adverse perinatal outcomes, but its contribution to severe maternal morbidity (SMM) remains unclear. We examined the association between IPI and SMM, using data linked across sequential pregnancies to women in California during 1997–2012. Adjusting for confounders measured in the index pregnancy (i.e., the first in a pair of consecutive pregnancies), we estimated adjusted risk ratios for SMM related to the subsequent pregnancy. We further conducted within-mother comparisons and analyses stratified by parity and maternal age at the index pregnancy. Compared with an IPI of 18–23 months, an IPI of <6 months had the same risk for SMM in between-mother comparisons (adjusted risk ratio (aRR) = 0.96, 95% confidence interval (CI): 0.91, 1.02) but lower risk in within-mother comparisons (aRR = 0.76, 95% CI: 0.67, 0.86). IPIs of 24–59 months and ≥60 months were associated with increased risk of SMM in both between-mother (aRR = 1.18 (95% CI: 1.13, 1.23) and aRR = 1.76 (95% CI: 1.68, 1.85), respectively) and within-mother (aRR = 1.22 (95% CI: 1.11, 1.34) and aRR = 1.88 (95% CI: 1.66, 2.13), respectively) comparisons. The association between IPI and SMM did not vary substantially by maternal age or parity. In this study, longer IPI was associated with increased risk of SMM, which may be partly attributed to interpregnancy health.

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.

Change in modifiable maternal characteristics and behaviours between consecutive pregnancies and offspring adiposity: A systematic review

Causal evidence links modifiable maternal exposures during the periconceptional period with offspring obesity. The interconception period may be an important time to intervene. We systematically identified studies examining change in modifiable maternal exposures between pregnancies and offspring adiposity. We searched for longitudinal studies published between 1990 and 2019, which included measurements taken on at least two occasions in the period from 1 year prior to the conception of the first birth to the time of the second birth, and which included a measure of adiposity in second, or higher order, siblings. Age, ethnicity and genetics were not considered modifiable; all other factors including length of the interpregnancy interval were. Eleven studies satisfied the inclusion criteria. Higher interpregnancy weight gain or loss, maternal smoking inception, mothers smoking in their first pregnancy and quitting, increasing the number of cigarettes smoked and longer interpregnancy intervals were positively associated with adiposity in second or higher order children. Vaginal birth after caesarean delivery was protective. Further research is needed to ascertain whether the risk of adiposity is fixed based on first pregnancy exposures or if interpregnancy change alters the risk for a subsequent child. This can inform the type and effectiveness of interventions for mothers prior to a subsequent pregnancy.

New Partner, New Order? Multipartnered Fertility and Birth Order Effects on Educational Achievement

A substantial amount of research shows that younger siblings perform worse than their older sisters and brothers in several socioeconomic outcomes, including educational achievement. Most of these studies examined stable families and excluded half-siblings. However, the increasing prevalence of multipartnered fertility implies that many children grow up in nonnuclear families. We examine whether there is evidence for birth order effects in this context, which offers an opportunity to test and potentially expand the explanatory scope of the two main theories on birth order effects. We use comprehensive Norwegian registry data to study siblings in the 1985-1998 cohorts born to mothers or fathers who parented children with at least two partners. We provide evidence for negative effects of birth order on lower secondary school grades in both cases. Children born to fathers displaying multipartnered fertility tend to have lower grades than older full siblings but perform more similarly or better compared with older half-siblings. For siblings born to mothers with the multipartnered fertility pattern, later-born siblings do worse in school compared with all older siblings. This indicates that negative birth order effects tend to operate either within or across sets of full siblings, depending on the sex of the parent displaying multipartnered fertility. We argue that these findings can be explained by a combination of resource dilution/confluence theory and sex differences in residential arrangements following union dissolutions. We also suggest an alternative interpretation: maternal resources could be more important for generating negative birth order effects.

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.

Interpregnancy intervals and perinatal and child health in Sweden: A comparison within families and across social groups

A large body of research has shown that children born after especially short or long birth intervals experience an elevated risk of poor perinatal outcomes, but recent work suggests this may be explained by confounding by unobserved family characteristics. We use Swedish population data on cohorts born 1981-2010 and sibling fixed effects to examine whether the length of the birth interval preceding the index child influences the risk of preterm birth, low birth weight, and hospitalization during childhood. We also present analyses stratified by salient social characteristics, such as maternal educational level and maternal country of birth. We find few effects of birth intervals on our outcomes, except for very short intervals (less than seven months) and very long intervals (>60 months). We find few differences in the patterns by maternal educational level or maternal country of origin after stratifying by the mother's highest educational attainment.

Birth order is associated with caries development in young children: a register-based cohort study

BACKGROUND

Birth order has been shown to affect the health of the child; less is known, however, about how birth order affects caries development in children. Thus, the present study investigated the association between birth order and dental caries development in young children.

METHODS

This retrospective registry-based cohort study included all children born in 2000-2003 who were residing in Stockholm County, Sweden, at age 3 years (n = 83,147). The study followed the cohort until subjects reached 7 years of age. Children with registry data on dental examinations and sociodemographic characteristics at ages 3- and 7 years constituted the final study cohort (n = 65,259). The outcome variable was "caries increment from age 3- to 7 years" (Δdeft > 0) and the key exposure, "birth order", was divided into five groups. A forward stepwise logistic binary regression was done for the multivariate analysis with adjustments for sociodemographic factors.

RESULTS

At age 3 years, 94% had no fillings or manifest caries lesions. During the study period, 22.5% (n = 14,711) developed dental caries. The final logistic regression analysis found a statistically significant positive association between birth order and caries increment. Further, excess risk increased with higher birth order; with the mother's first-born child as reference, risk for the second-born child was OR 1.17, 95% CI = 1.12-1.23; for the third-born child, OR 1.47, 95% CI = 1.38-1.56; for the fourth-born child, OR 1.69, 95% CI = 1.52-1.88; and for the fifth-born or higher birth-order child, OR 1.84, 95% CI = 1.58-2.14.

CONCLUSIONS

These findings show that birth order influences caries development in siblings, suggesting that birth order can be regarded as a predictor for caries development in young children. This factor may be helpful in assessing caries risk in preschool children and should be considered in caries prevention work in young children with older siblings.

Shorter birth intervals between siblings are associated with increased risk of parental divorce

Birth intervals are a crucial component of fertility behaviour and family planning. Short birth intervals are associated—although not necessarily causally—with negative health-related outcomes, but less is known about their associations with family functioning. Here, the associations between birth intervals and marital stability were investigated by Cox regression using a nationally representative, register-based sample of individuals with two (N = 42,481) or three (N = 22,514) children from contemporary Finland (observation period 1972–2009). Shorter interbirth intervals were associated with an increased risk of parental divorce over a ten-year follow-up. Individuals with birth intervals of up to 1.5 years had 24–49 per cent higher divorce risk compared to individuals whose children were born more than 4 years apart. The pattern was similar in all socioeconomic groups and among individuals with earlier and later entry to parenthood. Our results add to the growing body of research showing associations between short birth intervals and negative outcomes in health and family functioning.