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Bariatric surgery and pregnancy

Pregnancy after bariatric surgery is safe

No significant difference found in the risk of gestational diabetes, admission to neonatal intensive care unit or perinatal death
Additional study says there is no evidence to delay pregnancy beyond 12 months post-surgery
Literature review finds pregnancy post-surgery is safe

The weight of newborns whose mothers have had bariatric surgery does not differ significantly compared with new-borns from mothers who have not had surgery, according to a study published in the American Journal of Obstetrics & Gynecology.

The paper, the first of three published by researchers from the Department of Obstetrics and Gynecology, Hvidovre University Hospital, Denmark, reported that there was no statistically significant difference between the groups regarding the risk of gestational diabetes mellitus, preeclampsia, labour induction, caesarean section, post-partum haemorrhage, admission to neonatal intensive care unit or perinatal death.

Although the infants in the group of mothers who have had bariatric surgery had shorter mean gestational age (274 vs. 278 days, p<0.001), lower mean birth weight (3,312g vs. 3,585g, p<0.001), lower risk of being large-for-gestational-age and higher risk of being small-for-gestational-age, compared to new-borns in the non-surgery group, this too was not clinically significant.

Lead author of the study, Dr Mette M Kjaer told Reuters Health that despite expecting to find “a positive impact on maternal complications, especially the risk of gestational diabetes mellitus, after matching for BMI we did not find any difference between the groups.”

The researchers identified 339 women who had given birth after bariatric surgery (84.4% gastric bypass) and matched them to 1,277 women of similar age, BMI and delivery date and who had not had a bariatric procedure. The average BMI in the surgery group was 32.4 compared with 32.2 in the non-surgery group (p=0.44).

"Paradoxically, babies both small- or large-for-gestational-age are at increased risk of later obesity and metabolic syndrome," said Kjaer.

Although most women and their babies do well after bariatric surgery she added that special attention should be paid to monitoring foetal growth and the need for nutritional and vitamin supplementation.

Delaying pregnancy

In the second paper published in the Obesity Surgery journal, the authors concurred with a previous study that women should wait at least 12 months before trying for a baby following bariatric surgery, claiming that there is no evidence to support delaying pregnancy beyond the first post-operative year.

The researchers used the national register-based cohort study that covered all Danish deliveries during 2004-2010 in women with prior Roux-en-Y gastric bypass surgery. For the study, they compared the risk of adverse pregnancy and neonatal outcomes between women who conceived within the first postoperative year and women who conceived later.

From 286 women who had a single delivery after gastric bypass surgery, 158 women conceived within the first year and 128 later. They report that there was no statistically significant difference (p > 0.05) between the two groups regarding neonatal birth weight, gestational age, risk of preeclampsia, gestational diabetes mellitus, labour induction, caesarean section, postpartum haemorrhage, preterm birth, small for gestational age, large for gestational age, or the need of neonatal intensive care.

However, the researchers note that the optimal time for pregnancy after gastric bypass is not yet known.

In the third paper, a literature review published in the Acta Obstetricia et Gynecologica Scandinavica journal, the researchers reported that “pregnancy after bariatric surgery seems safe, although larger studies matching or adjusting for BMI are needed to improve the surveillance of these pregnancies and to assist in preventing adverse outcomes.”

The review included 17 papers, comparing pregnancies in women with prior bariatric surgery to pregnancies in a control group without surgery. They investigators report that there was considerable heterogeneity in study design and six of the studies included less than 50 women with bariatric surgery. Eight studies described lower birth weight and lower risk of macrosomia after bariatric surgery, although in six studies there no difference.

Five studies indicated a higher risk of small-for-gestational age infants, but only compared with non-obese women or severely obese controls; there was no difference in gestational length.

They found a single study that suggested a higher risk of birth defects after surgery and the risk of pre-eclampsia and gestational diabetes was found to be lower post-surgery.

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