More recent studies have focused on interventions to help women limit their weight gain during pregnancy. Although none of the four trials conducted in North American populations and reviewed by the IOM was completely successful in helping women limit their gestational weight gain and adhere to the 1990 guidelines, two European studies demonstrate that it's possible to motivate obese pregnant women to limit their weight gain during pregnancy to 6-7 kg. The interventions involved individual dietary or motivational counseling, and in one of the studies, the provision of specially designed aqua aerobics classes.
In general, interventions described in the literature have included counseling, the provision of unique physical activity classes, dietary prescription, and even daily recording of dietary intake.
▸ But do not encourage weight loss. Some investigators have recently proposed that obese women should consider weight loss during pregnancy in order to decrease adverse perinatal outcomes. It is my opinion that while women should avoid excessive weight gain, they should not be advised to lose weight until additional investigation shows that there are benefits and no adverse consequences to the mother and/or fetus.
There are obligatory physiological changes that for most women result in a “net maternal weight gain”: on average, 4-5 kg of weight at term represents the fetus, the placenta, and amniotic fluid.
For reasons that we don't fully understand, some obese women do not gain weight during pregnancy, or may actually lose weight, and still have a healthy baby. These women may have a decrease in energy expenditure in pregnancy and a subsequent decrease in intake, and/or there may be other physiologic issues at work.
As long as such a patient is eating well, seeing a nutritionist, and does not have ketonemia/ketonuria, and her baby is growing well, I would not encourage excessive intake in order to meet a particular weight gain target. I would just monitor her carefully.
The bottom line: Until we learn more about the safety of intentional weight loss during pregnancy, we face a delicate balancing task. On one hand, we need to appreciate that some women do not gain weight during pregnancy and should not necessarily be urged to gain an arbitrary amount while, on the other hand, we should not encourage these women to lose weight.
▸ Consider bariatric surgery to be a tool in your armamentarium. Population studies and reports of long-term outcomes from the United States and Scandinavia suggest that bariatric surgery has potential long-term benefits—in terms of weight loss and improvement in metabolic function—for women of reproductive age who do not have success with lifestyle measures and medical treatments.
In our practice, we often refer women after delivery to see our obesity specialist, who institutes medical therapy and will move on to consideration of bariatric surgery if the medical therapy is not successful. Experts have determined that bariatric surgery may be considered in women with a BMI greater than 35 (class II obesity) who have significant medical problems such as hypertension or diabetes, or in women who have a BMI greater than 40 (class III obesity) and no obvious medical complications.
ACOG's committee opinion No. 315 from 2005 includes various recommendations about how long to delay pregnancy after surgery (12-18 months after laparoscopic adjustable gastric banding, for example), and what vitamin supplementation is necessary. Women who have laparoscopic adjustable gastric banding should be monitored by both their obstetrician and bariatric surgeon during pregnancy, according to the ACOG committee's recommendations (Obstet. Gynecol. 2005;106:671-5).
▸ Don't “miss the forest for the trees.” When encountering various complaints and problems during pregnancy, think of the underlying obesity and not only the effects of pregnancy. Because obese women have an increased risk of developing or having manifestations of the metabolic syndrome—hypertension, proteinuria, dyslipidemia, and diabetes—we are seeing an increase in medical problems that in the past have been diagnosed primarily in older nonpregnant patients. Sleep apnea and nonalcoholic fatty liver disease are examples.
A woman who has shortness of breath or declining levels of oxygen saturation post partum, particularly after a cesarean delivery, may actually have sleep apnea, for instance, rather than a pulmonary embolism or pregnancy-related changes in tidal volume.
Similarly, elevated liver function tests may be an indication of nonalcoholic fatty liver disease rather than a manifestation of severe preeclampsia or the HELP syndrome. Non-alcoholic fatty liver disease is actually the most common reason today for a woman of reproductive age to have elevated liver function tests. Increasingly, it is becoming a more common diagnosis in the obese patient. Obesity, increased estrogen concentrations, elevated lipids, and increased insulin resistance have all been recognized as factors contributing to the development of non-alcoholic fatty liver disease.