Bariatric surgery is internationally performed as a treatment option in obesity to achieve significant and sustained weight loss. There is an increasing number of women having pregnancies after bariatric surgery with mixed maternal and fetal outcomes, with a limited number of large, matched studies.

This study aimed to describe the type of prepregnancy bariatric surgery, analyze maternal, pregnancy, and offspring outcomes relative to matched women, and assess the impact of prepregnancy bariatric surgery on fetal growth, particularly the proportions of small for gestational age and large for gestational age infants.

A cross-sectional, matched study was performed using a statewide hospital and perinatal data register. A total of 2018 births of 1677 women with prepregnancy bariatric surgery were registered between 2013 and 2018. Of those, 1282 were included and analyzed, matched in a 1:10 ratio for age, parity, smoking status, and body mass index to women without bariatric surgery. The first singleton pregnancy following bariatric surgery for each woman was used for analysis. Pregnancy and neonatal outcomes based on International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification, and neonatal birth records were analyzed. Multivariable logistic regression was used to estimate the association between small for gestational age and large for gestational age infants and prepregnancy bariatric surgery.

Of the 1282 women, 93% had undergone laparoscopic sleeve gastrectomy. Among women with prepregnancy bariatric surgery compared with matched women, offspring had lower absolute birthweight (3223±605 vs 3418±595 g; P<.001), and a lower rate of large for gestational age infants (8.6% vs 14.1%; P<.001) and a higher rate of small for gestational age infants (10.7% vs 7.3%; P<.001) were found. Offspring of mothers with prepregnancy bariatric surgery were more likely to be born preterm (10.5% vs 7.8%; P=.007). Fewer women with previous bariatric surgery were diagnosed with gestational diabetes mellitus (15% vs 20%; P<.001) or pregnancy-induced hypertension (3.7% vs 5.4%; P=.01). In the adjusted model, prepregnancy bariatric surgery was associated with lower risk of large for gestational age (odds ratio, 0.54; 95% confidence interval, 0.44–0.66) and higher risk of small for gestational age infants (odds ratio, 1.78, 95% confidence interval, 1.46–2.17).

These data suggest that prepregnancy bariatric surgery was associated with a reduction in several obesity-related pregnancy complications at the expense of more preterm births and small for gestational age offspring.

(6.22 Mo)