Bariatric Surgery May Reduce Risk for Hypertensive Disorders in Pregnancy

Bariatric surgery may reduce risk for hypertensive disorders in subsequent pregnancy, according to the results of a retrospective analysis of US insurance claims data published online April 13 in the British Medical Journal.

"Hypertensive disorders of pregnancy are increasing in prevalence, even more so now with the increasing rates of obesity," Amitasrigowri S. Murthy, MD, MPH, FACOG, director of reproductive choice, Department of Obstetrics and Gynecology, Bellevue Hospital Center, New York City, told Medscape Ob/Gyn & Women's Health when asked for independent comment. "Obesity is related to multiple medical problems and is associated with adverse perinatal outcomes, as are hypertensive disorders of pregnancy."

The goal of this retrospective cohort study, by Wendy L. Bennett, MD, and colleagues from Johns Hopkins University School of Medicine in Baltimore, Maryland, was to determine whether women who had a delivery after bariatric surgery had lower rates of hypertensive disorders in pregnancy than women who had a delivery before bariatric surgery.

"Any intervention that decreases obesity would be successful in decreasing hypertensive disorders, but most interventions are not successful or are successful only temporarily," said Dr. Murthy, who is also assistant professor at New York University School of Medicine. "Bariatric surgery is now considered the most effective treatment available for obesity. With this decrease in weight, other comorbidities decrease in prevalence, particularly hypertensive disorders. Decrease in weight in women could also be associated with decreased numbers of adverse outcomes in pregnancy."

Using claims data for 2002 to 2006 from 7 US insurance plans, the investigators identified 585 women aged 16 to 45 years who had undergone bariatric surgery, had at least 1 pregnancy and delivery, and had continuous insurance coverage during pregnancy plus 2 weeks after delivery. The primary study endpoint was hypertensive disorders in pregnancy identified from International Statistical Classification of Diseases and Related Health Problems, Ninth Edition, codes, and the independent variable was the timing of delivery — before vs after bariatric surgery. For each type of hypertensive disorder in pregnancy, odds ratios (ORs) and confidence intervals (CIs) were calculated from logistic regression.

Of the 585 participants, 269 delivered before bariatric surgery and 316 delivered after surgery. Most women (82%; 477) had gastric bypass surgery. Compared with women who delivered after surgery, those who delivered before surgery were younger at delivery (mean age, 31.3 vs 32.5 years; P < .002) and had higher rates of preexisting diabetes and gestational diabetes mellitus.

After adjustment for age at delivery, multiple pregnancy (twins or more), surgical procedure, preexisting diabetes, and insurance plan, rates of hypertensive disorders of pregnancy were markedly lower in women who delivered after surgery than in those who delivered before surgery. For preeclampsia and eclampsia, OR was 0.20 (95% CI, 0.09 - 0.44); for chronic hypertension complicating pregnancy, OR was 0.39 (95% CI, 0.20 - 0.74); and for gestational hypertension, OR was 0.16 (95% CI, 0.07 - 0.37).

"Any intervention that could decrease adverse perinatal outcomes, particularly in the preconception period, is welcome," Dr. Murthy said. "This study clearly shows that a decrease in weight caused by surgery leads to a decrease in prevalence of hypertensive disorders of pregnancy."

Strengths of this study cited by Dr. Murthy include its design and use of a large claims database from all over the country, allowing better generalizability to women with obesity and concerns regarding hypertensive disorders in pregnancy.

"While a retrospective study, the design seems to be the best way to answer this question; picking other control groups may introduce other confounders that may skew the results," Dr. Murthy said. "The authors also included claims for both inpatient as well as outpatient care. This allowed for inclusion of assessments that may have impacted prenatal care and delivery information."

Limitations noted by Dr. Murthy include the inability to confirm information in the medical record, such as body mass index and other clinical factors needed to confirm the diagnosis of either obesity or hypertensive disorder, because the data were from a claims database.

"While data seem to suggest that discharge diagnosis is correct about half the time, there still remains a chance that incorrect coding may impact the results," Dr. Murthy said. "Neither is there included a way to connect the neonatal information about the delivery, nor is there a way to know if there were complications to the neonate arising from either the hypertensive disorder or the surgery."

In terms of further research, Dr. Murthy recommends long-term follow-up of mothers undergoing bariatric surgery before delivery to evaluate health-related and other quality-of-life issues and long-term weight management.

"Additional studies need to be done to ensure that there exists no adverse neonatal outcome, particularly as gastric bypass surgery is often associated with nutritional deficiencies in the mother," Dr. Murthy said. "Long-term follow up of those children delivered after surgery should be done to ensure no other developmental effects on infant growth."

The study authors point out the important clinical, public health, and policy implications of their findings. They suggest considering bariatric surgery in women of childbearing age who wish to start a family and who have a body mass index of 40 kg/m2or more, or a body mass index of 35 to 40 kg/m2 with associated conditions.

"The preconception visit is a vitally important one — it can lead to improved health in all women attempting pregnancy," Dr. Murthy concluded. "Addressing weight concerns at this visit, while not easy for both patient and provider, can lead to improved health outcomes for both mother and neonate. This is difficult, however, as over half of pregnancies occurring in the US are unplanned."

The data set used in this study was created for a research project on the patterns of obesity care within selected BlueCross BlueShield plans. The original development of the data set was supported by unrestricted research grants from Ethicon Endo-Surgery, Pfizer, and GlaxoSmithKline. The study authors have disclosed no relevant financial relationships. Dr. Murthy is on the speaker board for Schering Plough as a trainer for Implanon, but otherwise has disclosed no relevant financial relationships.

source: medscape