Clinical Review

Obesity in pregnancy: Risks and interventions by gestational stage

OBG Manag. 2003 September;15(9):27-38

References

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Postpartum: Longer hospitalization

Although they did not provide the reasons, Hood and Dewan²⁵ linked obesity with prolonged postpartum hospitalization. They found obese patients to have significantly longer hospital stays, regardless of the type of delivery:

Following vaginal delivery, postpartum hospitalization was 3.8±2.4 days among overweight patients and 2.9±2.1 days among controls.
After cesarean delivery, obese patients were in the hospital for 7.3±5.0 days; nonobese, for 5.4±3.1 days.

One study found the use of a subcutaneous drain or subcutaneous suture decreased the rates of wound infection or separation among obese women undergoing cesarean.

Cesarean complications

Obesity is a specific risk factor for several operative complications, including hemorrhage during surgery, postoperative wound infections, aspiration, and pulmonary embolism. A case-control study by Naef et al²⁶ revealed that a weight of more than 250 lb has an odds ratio of 13.1 (95% confidence interval, 1.7 to 102.7) for hemorrhage (decrease in hematocrit of 10% or greater, estimated blood loss greater than 1,500 mL, or packed red blood cell administration) during abdominal delivery.

Multiple studies have shown obesity to be a risk factor for postoperative wound infections.^27-30 For example, Johnson et al³⁰ reported a wound infection rate of 37.6% for the obese parturient and 10.2% for those of normal weight (P<.001>

The link between excess weight and infectious morbidity may be secondary to the increased subcutaneous tissue layer and accumulation of loculated fluid. In 2000, Vermillion et al³¹ published a study that looked at 140 women who had cesarean deliveries. Initially, a univariate analysis identified the risk factors for wound infection as maternal weight (a mean of 82.8 kg±18.6 kg in the uninfected population versus 99.4 kg±33.3 kg in the infected population), BMI (44.5±2.1 for uninfected versus 49.7±6.3 for infected), and thickness of subcutaneous tissue (2.3 cm±1.2 cm for uninfected versus 4.1 cm±1.8 cm for infected). After a multiple logistic regression analysis, however, subcutaneous tissue thickness was the only significant risk factor confirmed. A potential explanation for this finding is that the blood supply to subcutaneous fat is relatively poor.

Reducing infection. By modifying surgical techniques, physicians may be able to decrease the rate of wound infection among overweight parturients. Naumann et al³² randomized closure versus nonclosure of the subcutaneous tissue in 245 patients with at least 2 cm of adipose tissue. There was a significant difference in the incidence of overall wound disruptions (14.5% versus 26.6%)—specifically, seroma formation (5.1% versus 17.2%)—between the closure and nonclosure groups, respectively, but no significant difference in wound infections (6% versus 7.8%).

There is no consistent evidence that obesity alone is associated with poor perinatal outcome.

Allaire et al³³ showed that the use of a subcutaneous drain or subcutaneous suture decreased the rates of wound infection or separation among obese women undergoing cesarean delivery. The incidence dropped from 30.8% when neither was used to 15.4% with suture and 4.2% with a drain.

While several investigators have noted the increased rate of postoperative complications among obese parturients, few have systematically analyzed their etiology. Wolfe et al³⁴ reviewed the antepartum and intrapartum variables among 107 consecutive obese parturients (all at least 200 lb) who had cesarean deliveries. Using multivariate analysis, the investigators noted that various degrees of obesity, preexisting medical conditions, the type of skin incision, and the type of anesthesia were not risk factors for postpartum infectious sequelae. Only 2 factors—both of which were under the control of physicians—contributed to morbidity: duration of cesarean delivery and operative blood loss. According to their regression equation, if surgical time was decreased from 1.5 hours to 1 hour, the postoperative stay would decrease by 1 day. These authors did not comment on the estimated blood loss or drop in hematocrit threshold that would minimize postoperative complications.

What about the neonate?

Interestingly, there is no consistent evidence that obesity alone is associated with poor perinatal outcome. A case-control study by Perlow et al³⁵ reported the outcomes of 111 neonates born to obese mothers. These infants were more likely to weigh less than 2,500 g or more than 4,000 g, to have intrauterine growth restriction, and to require admission to a neonatal intensive care unit. However, when patients with prepregnancy diagnoses of chronic hypertension or insulin-requiring diabetes mellitus were excluded, perinatal outcome was similar for obese and nonobese mothers. Garbaciak et al³⁶ reported similar results: They showed that only obese patients with antepartum complications had an increase in perinatal mortality. Two other studies showed no increase in perinatal morbidity or mortality among obese subjects.^19,27 It seems, therefore, that the risk for adverse perinatal outcomes may be related to underlying medical diseases rather than excessive weight.