Maternal body mass index and risk of intraventricular hemorrhage in preterm infants

The association of maternal overweight on long-term neurodevelopmental outcomes in premature infants (< 29 weeks) at 18-24 months corrected age

OBJECTIVE

To determine the association of maternal pre-pregnancy body mass index (BMI) and neurodevelopmental impairment (NDI) at 18-24 months corrected age (CA) in infants born < 29 weeks gestation.

STUDY DESIGN

Infants born between 2005 and 2015 at < 29 weeks gestation were included. BMI was categorized into BMI1 [18.5-24.9 kg/m2], BMI2 [25-29.9 kg/m2], BMI3 [ ≥ 30 kg/m2]. Primary outcome was death or NDI (Bayley-III scores < 85, cerebral palsy, hearing or visual impairment). Univariate and multivariate analysis were used.

RESULTS

There were 315 infants in BMI1, 235 in BMI2, and 147 in BMI3 groups. Adjusted odds ratio (aOR) of death or NDI in BMI2 vs. BMI1 and BMI3 vs BMI1 groups were 1.33 (95% CI 0.86-2.06) and 0.76 (95% CI 0.47-1.22). Adjusted odds ratio of Bayley-III language composite < 85 was 2.06 (95% CI 1.28-3.32).

CONCLUSION

Pre-pregnancy BMI was not associated with death or NDI in extremely preterm infants. Infants born to overweight mothers had higher odds of low language scores.

Linked birth cohort files for perinatal health research: California as a model for methodology and implementation

PURPOSE

Rigorous perinatal epidemiologic research depends on population-based parental and neonatal sociodemographic and clinical data. Here we describe the creation of linked birth cohort files, an enriched data source that combines information from vital records with maternal delivery and infant hospital encounter records.

METHODS

Probabilistic linkage techniques were used to link vital records (i.e., birth and fetal death certificates) from the California Department of Public Health with hospital inpatient, ambulatory surgery and emergency department encounter data for mothers and infants from the California Department of Health Care Access and Information.

RESULTS

From 2012 to 2018, 95% of live birth records were successfully linked to maternal and newborn hospital records while 85% of fetal death records were linked to a maternal delivery record. Overall, 93% of postnatal hospital encounters of infants (i.e., <1 year old) were matched to a linked record.

CONCLUSIONS

The linked birth cohort files is a rich resource opening many possibilities for understanding perinatal health outcomes and opportunities for linkage to longitudinal, social determinant, and environmental data. To optimally use this file for research, analysts should evaluate possible shortcomings or biases of the data sources being linked.

Critical examination of relationships between early growth and childhood overweight in extremely preterm infants

OBJECTIVES

To identify the prevalence and risk factors for childhood overweight and obesity (OWO) at 3-year corrected age in children born <1500 g <29 weeks gestation.

STUDY DESIGN

A multicentre retrospective cohort study for preterm infants admitted to neonatal intensive care units between 2001 and 2014.

RESULTS

Data were available for 911 (89.4%) of the 1019 infants who met the inclusion criteria. Of them, 22 (2.4%) had OWO. There were no associations between OWO and being small for gestational age (RR = 1.3, 95% confidence interval (CI): 0.3-5.4) or weight <10th percentile at 36 weeks (RR = 1.1, 95% CI: 0.4-2.8). OWO was associated with low maternal education (RR = 7.4, 95% CI: 2.1-26), maternal diabetes (RR = 5.2, 95% CI: 1.9-15) and neonatal brain injury (RR = 4.9, 95% CI: 1.8-14). Adjusting for concurrent child weight at 3 years of age resulted in an overadjustment bias.

CONCLUSION

Small size at birth or at 36 weeks gestation in extremely preterm infants is not associated with increased risk of early childhood overgrowth or obesity.

CLINICAL TRIAL REGISTRATION

NCT03064022.

Maternal body-mass-index and neonatal brachial plexus palsy in a California cohort

OBJECTIVE

To evaluate risk factors and describe the association between maternal pre-pregnancy body-mass-index (BMI) and neonatal brachial plexus palsy (BPP) in vaginal deliveries with and without shoulder dystocia.

METHODS

This is a retrospective cohort study of singleton, non-anomalous, term vaginal deliveries in California (2007-2011). Deliveries were classified as with or without shoulder dystocia. Our primary outcome was BPP and the independent variable of interest was maternal pre-pregnancy BMI, which was categorized as underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), obesity I (30-34.9 kg/m²), obesity II (35-39.9 kg/m²) and obesity III (≥40 kg/m²). We evaluated demographics, maternal, labor, and neonatal characteristics using chi-squared tests and assessed the association of pre-pregnancy BMI with BPP using multivariable logistic regression models.

RESULTS

In our cohort of 1,395,761 women, there were 21,463 deliveries with shoulder dystocia and 1,374,298 deliveries without shoulder dystocia. Among deliveries with shoulder dystocia, BPP was observed more frequently in neonates born to women with BMI categorized as overweight (32% vs. 29%; p < .001), obesity I (22% vs. 14%; p < .001), obesity II (10% vs. 6%; p < .001), and obesity III (8% vs. 3%; p < .001). After adjusting for confounders, the odds of BPP in deliveries with shoulder dystocia was significantly higher for women who were overweight (aOR = 1.65; 95% CI: 1.35-2.01), obesity I (aOR = 2.33; 95% CI: 1.86-2.90), obesity II (aOR = 2.56; 95% CI: 1.92-3.40), and obesity III (aOR = 3.80; 95% CI: 2.75-5.25). In deliveries without shoulder dystocia, BPP was more common in women with a BMI that was overweight (29% vs. 25%; p < .001), obesity I (17% vs. 11%; p < .001), obesity II (9% vs. 4%; p < .001), and obesity III (8% vs. 2%; p < .001). In this cohort, multivariable regression model showed similar results in women with a BMI that was overweight (aOR = 1.47; 95% CI: 1.19-1.81), obesity I (aOR = 1.99; 95% CI: 1.55-2.54), obesity II (aOR = 2.79; 95% CI: 2.04-3.83), and obesity III (aOR = 5.05; 95% CI: 3.63-7.03).

CONCLUSION

Rising maternal pre-pregnancy BMI is associated with an increased risk of BPP in vaginal deliveries with and without shoulder dystocia. Preconception interventions targeting weight management may be beneficial in reducing BPP in all deliveries.

In-hospital mortality and morbidity among extremely preterm infants in relation to maternal body mass index

OBJECTIVE

The objective of this paper is to compare in-hospital survival and survival without major morbidities in extremely preterm infants in relation to maternal body mass index (BMI).

METHODS

This retrospective cohort study included extremely preterm infants (gestational age 220/7-286/7 weeks). This study was conducted at National Institute of Child Health and Human Development Neonatal Research Network sites. Primary outcome was survival without any major morbidity.

RESULTS

Maternal BMI data were available for 2415 infants. Survival without any major morbidity was not different between groups: 30.8% in the underweight/normal, 28.1% in the overweight, and 28.5% in the obese (P = 0.65). However, survival was lower in the obese group (76.5%) compared with overweight group (83.2%) (P = 0.02). Each unit increase in maternal BMI was associated with decreased odds of infant survival (P < 0.01).

CONCLUSIONS

Survival without any major morbidity was not associated with maternal obesity. An increase in maternal prepregnancy BMI was associated with decreased odds of infant survival.

Trends in maternal prepregnancy body mass index (BMI) and its association with birth and maternal outcomes in California, 2007-2016: A retrospective cohort study

OBJECTIVE

To determine recent trends in maternal prepregnancy body mass index (BMI) and to quantify its association with birth and maternal outcomes.

METHODS

A population-based retrospective cohort study included resident women with singleton births in the California Birth Statistical Master Files (BSMF) database from 2007 to 2016. There were 4,621,082 women included out of 5,054,968 women registered in the database. 433,886 (8.6%) women were excluded due to invalid or missing information for BMI. Exposures were underweight (BMI < 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), and obese (≥ 30 kg/m2) at the onset of pregnancy. Obesity was subcategorized into class I (30.0-34.9 kg/m2), class II (35.0-39.9 kg/m2), and class III (≥ 40 kg/m2), while adverse outcomes examined were low birth weight (LBW), very low birth weight (VLBW), macrosomic births, preterm birth (PTB), very preterm birth (VPTB), small-for-gestational-age birth (SGA), large-for-gestational-age birth (LGA), and cesarean delivery (CD). Descriptive analysis, simple linear regression, and multivariate logistic regression were performed, and adjusted odds ratios (AORs) with 95% confidence intervals (CIs) for associations were estimated.

RESULTS

Over the ten-year study period, the prevalence of underweight and normal weight women at time of birth declined by 10.6% and 9.7%, respectively, while the prevalence of overweight and obese increased by 4.3% and 22.9%, respectively. VLBW increased significantly with increasing BMI, by 24% in overweight women and by 76% in women with class III obesity from 2007 to 2016. Women with class III obesity also had a significant increase in macrosomic birth (170%) and were more likely to deliver PTB (33%), VPTB (66%), LGA (231%), and CD (208%) than women with a normal BMI. However, obese women were less likely to have SGA infants; underweight women were 51% more likely to have SGA infants than women with a normal BMI.

CONCLUSIONS

In California from 2007 to 2016, there was a declining trend in women with prepregnancy normal weight, and a rising trend in overweight and obese women, particularly obesity class III. Both extremes of prepregnancy BMI were associated with an increased incidence of adverse neonatal outcomes; however, the worse outcomes were prominent in those women classified as obese.