Birth spacing and risk of adverse pregnancy and birth outcomes: A systematic review and dose-response meta-analysis

Association between interpregnancy interval and adverse perinatal outcomes among subsequent twin pregnancies: a nationwide population-based study

BACKGROUND

The existing evidence on the association between interpregnancy interval (IPI) and pregnancy outcomes primarily focuses on singleton pregnancies, with limited research on twin pregnancies.

OBJECTIVE

This study aimed to investigate the association between IPI and adverse perinatal outcomes in twin pregnancies.

STUDY DESIGN

This population-based, retrospective cohort study analyzed data from the National Center for Health Statistics in the United States between 2016 and 2020. We included multiparous women aged 18 to 45 years with live-born twins without congenital anomalies, born between 26 and 42 weeks of gestation. Poisson regression models, adjusted for potential confounders, were used to evaluate the associations between IPI and adverse outcomes, including preterm birth (PTB) <36 weeks, small for gestational age (SGA), neonatal intensive care unit (NICU) admission, neonatal composite morbidity, and infant death. Missing data on covariates were managed using multiple imputations. Dose-response analyses were performed using the restricted cubic splines (RCS) approach. Subgroup analyses were stratified by maternal age, parity, and combination of neonatal sex. Sensitivity analyses were conducted using complete data and excluding pregnancies with intervening events during the IPI.

RESULTS

A total of 143,014 twin pregnancies were included in the analysis. Compared to the referent group (IPI of 18-23 months), an IPI of less than 6 months was associated with an increased risk of PTB<36 weeks (RR, 1.21; 95% confidence interval [95% CI]: 1.17-1.25), SGA (RR, 1.11; 95% CI: 1.03-1.18), neonatal composite morbidity (RR, 1.19; 95% CI: 1.12-1.27), NICU admission (RR, 1.18; 95% CI: 1.14-1.22), and infant death (RR, 1.29; 95% CI: 1.05-1.60). An IPI of 5 years or more was associated with an increased risk of PTB<36 weeks (RR, 1.18; 95% CI: 1.15-1.21), SGA (RR, 1.24; 95% CI: 1.18-1.30), neonatal composite morbidity (RR, 1.10; 95% CI: 1.05-1.15), and NICU admission (RR, 1.14; 95% CI: 1.11-1.17). The dose-response analyses showed that these outcomes had U-shaped or J-shaped associations with IPI. The associations between IPI and the outcomes slightly differed by advanced maternal age, parity, and combination of neonatal sex. The sensitivity analyses yielded similar results to the main findings.

CONCLUSION

Extreme IPI, less than 6 months or more than 5 years, was associated with adverse outcomes in twin pregnancies. IPI could be used as a predictor for risk stratification in high-risk twin pregnancies.

Interpregnancy maternal weight change is not associated with offspring weight and obesity at age 2 years

BACKGROUND

Weight retention between pregnancies is associated with increased risk of perinatal complications, but it is unclear whether there is an association with offspring weight status. This study aimed to determine whether maternal interpregnancy weight change is associated with offspring overweight/obesity, controlling for confounding variables.

SUBJECTS/METHODS

Routinely collected linked data from perinatal and child datasets, in Flanders, Belgium were used. Women having their first and second live births between 2009-2018 were included. The association between maternal interpregnancy weight change and overweight/obesity in the second child at 2 years was examined by logistical regression models.

RESULTS

A total of 33,172 women were included. 52.7% (n = 17478) had a stable interpregnancy BMI, 24.1% (n = 8024) and 8.5% (n = 2821) had moderate and substantial BMI increases respectively. At 2 years, 91.6% (n = 30383) of the second offspring had a healthy weight, 0.6% (n = 210), 7.0% (n = 2312) and 0.8% (n = 267) were in the underweight, overweight and obesity BMI categories respectively. Multivariate analysis showed no statistical evidence that maternal interpregnancy BMI change is independently associated with overweight/obesity in the second child. The strongest independent factors were the first child (sibling) being in the obesity category at 2 years (odds ratio [OR] 7.2, [95% CI, 5.49-9.45] and being born Large for Gestational Age (LGA) (2.13 [1.92-2.37]). The following variables were also independently associated with the outcome measure: maternal African origin (1.90 [1.59-2.26]), maternal obesity at start of first pregnancy (1.33 [1.16-1.53]), excessive gestational weight gain in the second pregnancy (1.15 [1.04-1.28]), being born after a < 1-year interpregnancy time interval (1.17 [1.05-1.30]) and not being exclusively breastfed at 12 weeks old (1.29 [1.10-1.52]).

CONCLUSION

Sibling obesity and being born LGA were most strongly independently associated with overweight/obesity at 2 years. This supports the need for family interventions and to address risk factors for development of LGA infants. There was no independent association with interpregnancy weight gain, contrary to what was hypothesised.

Child Protection System Removal and Short-Interval Births Among Individuals With Prenatal Substance Use

Child protection systems often intervene after substance-exposed births but are not designed to address the postpartum needs of the delivering parent. In this retrospective cohort study, we aimed to estimate the association between early child protection system removal and high-risk subsequent birth trajectories among a cohort of mothers with substance-exposed births in California. Of 6,893 births in 2015 with documented prenatal drug and alcohol exposure, 20.4% of mothers experienced child protection system removal within 30 days after birth. First-month child protection system removal was associated with short-interval birth (adjusted hazard ratio [HR] 1.61, 95% CI, 1.09-2.36) and short-interval birth with documentation of substance exposure (adjusted HR 3.17, 95% CI, 1.65-6.08). We found that child separation was associated with an increase, not a reduction, in subsequent substance-exposed births. These findings indicate the need for focused public health and supportive services to address the treatment, health care, family-building, and psychological needs of parents with substance use during pregnancy.

The effects of reproductive variables on child mortality in Ethiopia: evidence from demographic and health surveys from 2000 to 2016

BACKGROUND

Child mortality is a crucial indicator reflecting a country's health and socioeconomic status. Despite significant global improvements in reducing early childhood deaths, Southern Asia and sub-Saharan Africa still bear the highest burden of newborn mortality. Ethiopia is one of five countries that account for half of new-born deaths worldwide.

METHODS

This study examined the relationship between specific reproductive factors and under-five mortality in Ethiopia. A discrete-time survival model was applied to analyze data collected from four Ethiopian Demographic and Health Surveys (EDHS) conducted between 2000 and 2016. The study focused on investigating the individual and combined effects of three factors: preceding birth interval, maternal age at childbirth, and birth order, on child mortality.

RESULTS

The study found that lengthening the preceding birth interval to 18-23, 24-35, 36-47, or 48+ months reduced the risk of under-five deaths by 30%, 46%, 56%, and 60% respectively, compared to very short birth intervals (less than 18 months). Giving birth between the ages 20-34 and 35+ reduced the risk by 34% and 8% respectively, compared to giving birth below the age of 20. The risk of under-five death was higher for a 7th-born child by 17% compared to a 2nd or 3rd-born child. The combined effect analysis showed that higher birth order at a young maternal age increased the risk. In comparison, lower birth order in older maternal age groups was associated with higher risk. Lastly, very short birth intervals posed a greater risk for children with higher birth orders.

CONCLUSION

Not only does one reproductive health variable negatively affect child survival, but their combination has the strongest effect. It is therefore recommended that policies in Ethiopia should address short birth intervals, young age of childbearing, and order of birth through an integrated strategy.