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Bariatric surgery good for mom-to-be but not necessarily baby: study

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Having weight loss surgery before having a child may be good for the mother but not necessarily the baby, hints research published this month in Obstetrics and Gynecology.

“Our findings would suggest that bariatric surgery confers an improvement in maternal outcomes, but possibly at the expense of an increase in SGA (small for gestational age) neonates, preterm delivery and perinatal mortality,” report Dr. Jennifer Lesko and Dr. Alan Peaceman from the Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University in Chicago, Illinois.

An increasing number of reproductive age women are beginning pregnancy obese, which may contribute to multiple problems. Many of them are turning to bariatric surgery before becoming pregnant, when they fail to shed weight with diet and exercise.

“Other studies have demonstrated improved pregnancy outcomes for obese women who have undergone bariatric surgery, but those studies have generally been small,” Dr. Lesko told Reuters Health by email.

To investigate further, she and her colleague reviewed the charts of 70 women who had bariatric surgery and subsequently had a singleton pregnancy; nine women had laparoscopic gastric banding, 60 had either open or laparoscopic Roux-en-Y gastric bypass and one procedure was not specified.

The investigators compared the outcomes in these women to that of two control groups of women; 140 morbidly obese pregnant women (BMI similar to surgery patients pre-procedure) and 140 obese pregnant women (BMI similar to surgery patients before pregnancy).

“Our study has shown that overall there is an improvement in maternal outcomes in obese women who have undergone bariatric surgery – in particular, a large reduction in the risk of acquiring gestational diabetes,” Dr. Lesko said.

None of the women in the bariatric surgery group developed gestational diabetes, whereas 21 (16.4%) morbidly obese and 13 (9.3%) obese women did. “Our study supports the findings of other studies in the literature that have documented reductions in rates of gestational diabetes after bariatric surgery,” the investigators say.

There were no significant between-group differences in the rate of hypertensive disorders of pregnancy after bariatric surgery. However, the incidence of preterm birth was higher in the bariatric surgery group (14 cases; 20.0%) as compared with the obese group (9 cases; 6.4%).

In terms of neonatal outcomes, there was an overall decrease with bariatric surgery in larger infants (macrosomia), but an increase in the rate of smaller infants (SGA). “We believe that may have had to do with the fact that most of our study patients had undergone gastric bypass instead of lap-banding, the latter being a more common procedure in young women now. There is physiologic evidence that the lap-band has less effect on malnutrition,” Dr. Lesko said.

Babies born to women who had bariatric surgery weighed less at birth than their counterparts born to morbidly obese and obese women (mean birth weight 2,951 g vs 3,463 g and 3,351 g, respectively).

When birth weight was stratified by gestational age to evaluate fetal growth, 12 babies in the bariatric surgery group (17.4%) were SGA compared with seven (5.0%) in the morbidly obese group and 12 in the obese group (8.6%). The odds ratios for comparison of bariatric surgery patients with the morbidly obese and obese patients were 3.94 (p<0.01) and 2.25 (p=0.06), respectively.

There were also a “surprisingly high” number of perinatal deaths in the bariatric surgery group (four vs one in the morbidly obese group and none in the obese group); all were fetal deaths of nonanomalous fetuses between 22 and 40 weeks gestation.

All of these women had “normally grown fetuses, no evidence of hypertensive disorders of pregnancy or diabetes, and no significant pre-existing medical comorbidities. Three were preterm deliveries, one with cervical insufficiency at 22.5 weeks; this patient was the only patient who conceived within one year of her surgery. The fourth was a term intrauterine fetal demise without a laboratory or pathologic diagnosis,” the clinicians report.

Commenting on the perinatal mortality data, Dr. Lesko said: “It hasn’t been described in other similar studies so it may be a random finding. Additionally, it did not remain significant when we controlled for other maternal characteristics, except in the comparison of bariatric surgery patients with obese controls, but it was barely so, with wide confidence intervals, making it statistically less powerful. Furthermore, our study population was mostly gastric bypass, and these findings may not bear out in a population of reproductive-age women who are currently more likely to receive lap-bands, since they are purely restrictive and not malabsorptive in their mechanism, thus making their nutrition status more optimal. We believe that more studies would have to be done to determine if it is a true risk.”

Dr. Lesko and Dr. Peaceman conclude in their paper that, “In general, patients may be reassured that there are significant health benefits of bariatric surgery before pregnancy, but they also should be cautioned that there may be consequences for the pregnancy and the fetus.”

“We would recommend bariatric surgery for young obese and morbidly obese women who are interested in becoming pregnant, because we found that it lowers their risks of gestational diabetes in pregnancy. We would also recommend waiting at least a year after surgery before conceiving,” Dr. Lesko told Reuters Health.

“With the numbers of women of reproductive age seeking weight loss surgery increasing, it is important to consider the physiologic consequences of both restrictive and malabsorptive procedures and to work closely with patients and their surgeons to optimize both prepregnancy and gestational nutritional status,” the authors add in their paper.

The authors have no conflicts of interest.


Pregnancy Outcomes in Women After Bariatric Surgery Compared With Obese and Morbidly Obese Controls

Obstet Gynecol 2012;119:547-554.