# The impact of obesity on pregnancy outcomes in women with type 1 and type 2 diabetes across the NSW population: A retrospective cohort study

## TL;DR

This study compares pregnancy outcomes in women with type 1 and type 2 diabetes in NSW and finds that obesity increases risks for type 2 diabetes patients.

## Contribution

The study reveals that obesity significantly increases adverse outcomes in type 2 diabetes pregnancies but not in type 1 diabetes.

## Key findings

- Women with type 1 diabetes had higher odds of multiple adverse perinatal outcomes compared to type 2 diabetes patients.
- Obesity was associated with increased risks in type 2 diabetes pregnancies, including gestational hypertension and neonatal complications.
- Targeted weight interventions may reduce risks for women with type 2 diabetes during pregnancy.

## Abstract

To examine differences in pregnancy outcomes between women with type 1 (T1D) and type 2 diabetes (T2D) and assess the impact of concurrent obesity on adverse perinatal outcomes.

We retrospectively analysed singleton births of nulliparous mothers with T1D and T2D from 2016 to 2020, in New South Wales, Australia. The incidence of perinatal outcomes was compared between diabetes types. Logistic regression explored the impact of BMI and diabetes type on these outcomes, adjusting for relevant maternal characteristics.

In total, 568 women with T1D and 910 women with T2D were included. Women with T2D were older, had higher BMI, increased incidence of pre‐existing hypertension and smoking, and higher rates of socioeconomic disadvantage (p < 0.01). After stepwise adjustment for maternal covariates, women with T1D had higher odds of preeclampsia, caesarean section, maternal length of stay (LOS) >10 days, preterm birth, large‐for‐gestational age (LGA) neonates, neonatal resuscitation, neonatal hypoglycaemia, NICU admission, neonatal LOS >10 days and stillbirth (aOR >1, p < 0.05). Obesity conferred an increased odds of adverse outcomes in women with T2D but not T1D; these included gestational hypertension (aOR = 5.88, CI:1.38–25.15, p = 0.02), postpartum haemorrhage (aOR = 1.95, CI:1.18–3.23, p < 0.01), caesarean section (aOR = 2.29, CI:1.59–3.30, p < 0.01), LGA (aOR = 1.82, CI:1.13–2.93, p = 0.01), neonatal hypoglycaemia (aOR = 1.53, CI:1.02–2.30, p = 0.04) and neonatal resuscitation (aOR = 1.81, CI:1.19–2.76, p < 0.01).

Women with T1D had higher odds of adverse perinatal outcomes compared to those with T2D. Obesity increased risk in women with T2D, but not T1D, raising the possibility that targeted weight interventions in those with T2D may reduce the risk of adverse perinatal outcomes.