Aims
To evaluate the interaction effects of gestational diabetes (
GDM
) with obesity on perinatal outcomes.
Methods
A population‐based cohort study in Sweden excluding women without pre‐gestational diabetes with a singleton birth between 1998 and 2012. Logistic regression was performed to evaluate the potential independent associations of
GDM
and
BMI
with adverse perinatal outcomes as well as their interactions. Main outcome measures were malformations, stillbirths, perinatal mortality, low Apgar score, fetal distress, prematurity and Erb's palsy.
Results
Some 1,294,006 women were included, with a
GDM
prevalence of 1% (
n
= 14,833). The rate of overweight/obesity was 67.7% in the
GDM
‐group and 36.1% in the non‐
GDM
‐group. No significant interaction existed. Offspring of women with
GDM
had significantly increased risk of malformations, adjusted odds ratio (
aOR
) 1.16 (95% confidence intervals 1.06–1.26), prematurity,
aOR
1.86 (1.76–1. 98), low Apgar score,
aOR
1.36 (1.10–1.70), fetal distress,
aOR
1.09 (1.02–1.16) and Erb's palsy
aOR
2.26 (1.79–2.86). No risk for stillbirth or perinatal mortality was seen. Offspring of overweight (
BMI
25–29.9 kg/m
2
), obese (
BMI
30–34.9 kg/m
2
) and severely obese women (
BMI
≥ 35.0 kg/m
2
) had significantly increased risks of all outcomes including stillbirth 1.51 (1.40–1.62) to 2.85 (2.52–3.22) and perinatal mortality 1.49 (1.40–1.59) to 2.83 (2.54–3.15).
Conclusions
There is no interaction effect between
GDM
and
BMI
for the studied outcomes. Higher
BMI
and
GDM
are major independent risk factors for most serious adverse perinatal outcomes. More effective pre‐pregnancy and antenatal interventions are required to prevent serious adverse pregnancy outcomes among women with either
GDM
or high
BMI
.