The impact of inter-pregnancy interval on subsequent risk of preterm birth

Postpartum long-acting reversible contraception among privately insured: U.S. National analysis 2007-2016, by term and preterm birth

OBJECTIVES

To investigate postpartum long-acting reversible contraception (LARC) use among privately insured women, with specific consideration of use after preterm delivery.

STUDY DESIGN

We used the national IBM MarketScan Commercial Database to identify singleton deliveries from 2007 to 2016, spontaneous preterm birth, and follow-up ≤12 weeks postpartum. We assessed ≤12-week postpartum LARC placement overall and after spontaneous preterm deliveries, across study years. We examined timing of placement, rates of postpartum follow-up, and state-level variation in postpartum LARC.

RESULTS

Among 3,132,107 singleton deliveries, 6.6% were spontaneous preterm. Over the time period, total postpartum LARC use increased 4.8% to 11.7% for intrauterine devices (IUDs), 0.2% to 2.4% for implants. In 2016, those who experienced a spontaneous preterm birth were less likely to initiate postpartum IUDs compared to their peers (10.2% vs 11.8%, p < 0.001), minimally more likely to initiate implants (2.7% vs 2.4%, p = 0.04) and more likely to present for postpartum care (61.7% vs 55.9%, p < 0.001). LARC placement prior to hospital discharge was rare (preterm: 8 per 10,000 deliveries vs all others: 6.3 per 10,000 deliveries, p = 0.002). State-level analysis showed wide variation in postpartum LARC (range 6%-32%).

CONCLUSIONS

While postpartum LARC use increased among the privately insured 2007-2016, few received LARC prior to hospital discharge. Those experiencing preterm birth were no more likely to receive inpatient LARC. Postpartum follow-up remained low and regional variation of LARC was high, highlighting the need for efforts to remove barriers to inpatient postpartum LARC for all who desire it-public and privately insured alike.

IMPLICATIONS

Among the half of U.S. births that are privately insured, postpartum LARC is increasing after both term and preterm births, yet exceedingly few (<0.1%) received LARC prior to hospital discharge.

Association between maternal family history of hypertension and preterm birth: modification by noise exposure and multivitamin intake

OBJECTIVE

To measure the effect of maternal family history of hypertension on preterm birth (PTB) and to identify factors that modified this association.

METHODS

A case-control study was nested in a prospective cohort of the entire pregnant population in Wuhan, China, from 2011 to 2013. Home-visit interviews were scheduled for all PTBs and their controls, to collect extensive information on maternal exposures to behavioral, environmental, and intergenerational risk factors of PTB. The effects of maternal family history of hypertension on PTB were measured by logistic regression analyses, controlling for potential confounders. Potential effect modifiers were examined using stratified analyses.

RESULTS

There were 2393 PTBs and 4263 full-term births out of all eligible births. A positive association was observed between maternal family history of hypertension and PTB, after adjusted for potential confounders (adjusted odds ratio: 1.17 [1.03, 1.33]). A higher effect was observed when mothers were exposed to certain noise during pregnancy (adjusted odds ratio: 1.37 [1.14, 1.65]) and/or when they did not take multivitamins during pregnancy (adjusted odds ratio: 1.46 [1.20, 1.78]), whereas, this association was weaker and no longer significant when mothers took multivitamins during pregnancy (adjusted odds ratio: 1.00 [0.84, 1.19]) and/or when they were not exposed to certain noise during pregnancy (adjusted odds ratio: 1.01 [0.85, 1.12]). The modification effect from maternal multivitamin intake was significant on both spontaneous and medically indicated PTBs, and the modification effect from maternal exposure to certain noise was only significant on spontaneous PTB.

CONCLUSIONS

Increased PTB risk was observed for pregnant women with a family history of hypertension in Wuhan, China. This effect was stronger when pregnant women did not take multivitamin and/or exposed to certain noise during pregnancy, than those who took multivitamin and/or unexposed to certain noise.

The role of intervening pregnancy loss in the association between interpregnancy interval and adverse pregnancy outcomes

OBJECTIVE

To investigate whether intervening miscarriages and induced abortions impact the associations between interpregnancy interval after a live birth and adverse pregnancy outcomes.

DESIGN

Population-based cohort study.

SETTING

Norway.

PARTICIPANTS

A total of 165 617 births to 143 916 women between 2008 and 2016.

MAIN OUTCOME MEASURES

We estimated adjusted relative risks for adverse pregnancy outcomes using log-binomial regression, first ignoring miscarriages and induced abortions in the interpregnancy interval estimation (conventional interpregnancy interval estimates) and subsequently accounting for intervening miscarriages or induced abortions (correct interpregnancy interval estimates). We then calculated the ratio of the two relative risks (ratio of ratios, RoR) as a measure of the difference.

RESULTS

The proportion of short interpregnancy interval (<6 months) was 4.0% in the conventional interpregnancy interval estimate and slightly increased to 4.6% in the correct interpregnancy interval estimate. For interpregnancy interval <6 months, compared with 18-23 months, the RoR was 0.97 for preterm birth (PTB) (95% confidence interval [CI] 0.83-1.13), 0.97 for spontaneous PTB ( 95% CI 0.80-1.19), 1.00 for small-for-gestational age ( 95% CI 0.86-1.14), 1.00 for large-for-gestational age (95% CI 0.90-1.10) and 0.99 for pre-eclampsia (95% CI 0.71-1.37). Similarly, conventional and correct interpregnancy intervals yielded associations of similar magnitude between long interpregnancy interval (≥60 months) and the pregnancy outcomes evaluated.

CONCLUSION

Not considering intervening pregnancy loss due to miscarriages or induced abortions, results in negligible difference in the associations between short and long interpregnancy intervals and adverse pregnancy outcomes.

Interpregnancy intervals and adverse birth outcomes in high-income countries: An international cohort study

BACKGROUND

Most evidence for interpregnancy interval (IPI) and adverse birth outcomes come from studies that are prone to incomplete control for confounders that vary between women. Comparing pregnancies to the same women can address this issue.

METHODS

We conducted an international longitudinal cohort study of 5,521,211 births to 3,849,193 women from Australia (1980-2016), Finland (1987-2017), Norway (1980-2016) and the United States (California) (1991-2012). IPI was calculated based on the time difference between two dates-the date of birth of the first pregnancy and the date of conception of the next (index) pregnancy. We estimated associations between IPI and preterm birth (PTB), spontaneous PTB, and small-for-gestational age births (SGA) using logistic regression (between-women analyses). We also used conditional logistic regression comparing IPIs and birth outcomes in the same women (within-women analyses). Random effects meta-analysis was used to calculate pooled adjusted odds ratios (aOR).

RESULTS

Compared to an IPI of 18-23 months, there was insufficient evidence for an association between IPI <6 months and overall PTB (aOR 1.08, 95% CI 0.99-1.18) and SGA (aOR 0.99, 95% CI 0.81-1.19), but increased odds of spontaneous PTB (aOR 1.38, 95% CI 1.21-1.57) in the within-women analysis. We observed elevated odds of all birth outcomes associated with IPI ≥60 months. In comparison, between-women analyses showed elevated odds of adverse birth outcomes for <12 month and >24 month IPIs.

CONCLUSIONS

We found consistently elevated odds of adverse birth outcomes following long IPIs. IPI shorter than 6 months were associated with elevated risk of spontaneous PTB, but there was insufficient evidence for increased risk of other adverse birth outcomes. Current recommendations of waiting at least 24 months to conceive after a previous pregnancy, may be unnecessarily long in high-income countries.

Changes in Rates of Inpatient Postpartum Long-Acting Reversible Contraception and Sterilization in the USA, 2012-2016

OBJECTIVES

To examine recent rates of long-acting and permanent methods (LAPM) of contraception use during delivery hospitalization and correlates of their use.

METHODS

A retrospective cohort study utilizing the 2012-2016 National Inpatient Sample of hospitalizations in the United States of America. The International Classification of Diseases, 9th and 10th Revision, Clinical Modification codes were used to identify deliveries, inpatient long-acting reversible contraception (IPP LARC), and postpartum tubal ligation (PPTL). We conducted univariable and multivariable logistic regression to examine associations between demographic, clinical, hospital and geographical characteristics with likelihood of LAPM including IPP LARC and PPTL.

RESULTS

Our sample included 3,642,328 unweighted deliveries. The rate of IPP LARC increased from 34.6 to 54.9 per 10,000 deliveries (58.7%), while the rate of PPTL utilization decreased from 719.5 to 671.8 per 10,000 deliveries (6.6%) over the study period. In multivariable analysis of LAPM utilization versus neither, cesarean delivery (aOR 7.25, 95% CI 7.08-7.43) was associated with greater utilization. Native American (aOR 4.01, 95% CI 2.91-5.53) race was associated with increased use of IPP LARC compared to a non-long-acting method of contraception. Age between 18 and 29 years (aOR 6.21, 95% CI 5.42-7.11) was associated with greater use of IPP LARC versus PPTL. Delivering in a rural hospital ((aOR 0.09, 95% CI 0.06-0.12) and cesarean delivery (aOR 0.09, 95% CI 0.06-0.12) were associated with greater use PPTL versus IPP LARC.

CONCLUSIONS

The IPP LARC rate remains at less than 10% the PPTL rates in our study timeframe. The demonstrated variation in uptake of highly effective methods of contraception inpatient after delivery offer possible opportunities for better understanding and improvement in access.

Risk factors and child outcomes associated with short and long interpregnancy intervals

Previous research assessing consequences of interpregnancy intervals (IPIs) on child development is mixed. Utilizing a population-based US sample (n=5,339), we first estimated the associations between background characteristics (e.g., sociodemographic and maternal characteristics) and short (≤ 1 year) and long (> 3 years) IPI. Then, we estimated associations between IPI and birth outcomes, infant temperament, cognitive ability, and externalizing symptoms. Several background characteristics, such as maternal age at childbearing and previous pregnancy loss, were associated with IPI, indicating research on the putative effects of IPI must account for background characteristics. After covariate adjustment, short IPI was associated with poorer fetal growth and long IPI was associated with lower infant activity level; however, associations between short and long IPI and the other outcomes were neither large nor statistically significant. These findings indicate that rather than intervening to modify IPI, at-risk families may benefit from interventions aimed at other modifiable risk factors.