History
Preconception
Weight loss before pregnancy, whether achieved via surgical or nonsurgical methods, has been shown to be the most effective intervention to improve medical comorbidities, especially diabetes and hypertension. Obese women who have even small weight reductions before pregnancy may have improved pregnancy outcomes if they can avoid excessive weight gain once pregnant. [3, 4] Unfortunately, many women present for obstetrical care with an elevated body mass index (BMI).
It is recommended that women with a history of bariatric surgery wait 12-24 months before conceiving so that the fetus is not exposed to a rapid maternal weight loss environment and so that the patient can achieve full weight loss goals. Unfortunately, pregnancy may occur prior to this recommended time frame. The number of bariatric surgical procedures performed annually has dramatically increased, with many performed in reproductive-aged women. [4] Obstetric care providers can expect to manage increasing numbers of pregnancies in women with a history of bariatric surgery. (Refer to the Medscape article on bariatric surgery for additional information.)
Physical Examination
Calculating BMI and weight gain counseling
A thorough history taking and physical examination are completed at the first obstetrics visit. A woman’s BMI is also calculated at the initial visit. Obesity class I is defined as a BMI of 30-34.9 kg/m2, obesity class II as a BMI of 35-39.9 kg/m2, and obesity class 3 as a BMI greater than or equal to 40 kg/m2. This BMI is used to provide counseling guided by Institute of Medicine (IOM) recommendations for gestational weight gain during pregnancy. The IOM guidelines recommend a total weight gain of 15-25 lb for overweight women and 11-20 lb for obese women. [5]
These recommendations have some limitations. As mentioned earlier, a pregnancy-specific definition of obesity has not been standardized; thus, the pre-pregnancy BMI is typically used. BMI is imperfect, as it does not tell the whole story about the composition of a patient's body. One also needs to realize that weight gain is used simply as a proxy measure for the nutritional status of the woman. It is the actual nutritional quality of food intake that is critical and not simply the act of gaining weight. Women tend to gain the amount of weight they feel that they should. Unfortunately, obese women expect that a weight exceeding IOM recommendations is appropriate and in turn gain in excess of the recommendations. [6]
Nutritional status before and during early pregnancy may play an important role in ensuring successful pregnancy outcomes. Preconceptional and periconceptional intake of vitamin and mineral supplements is associated with a reduced risk of low birth weight and/or small-for-gestational-age infants and preterm deliveries. [7] Although inadequate weight gain and weight loss have been associated with small-for-gestational-age infants and even decreased lean body mass in the neonate, some studies have shown that in the pregnant woman with morbid obesity (BMI >40 kg/m2), weight gain of less than 10 lb and even weight loss in the setting of good balanced meals with appropriate caloric and nutritional intake may be acceptable. [8] Careful evaluation of the patient's diet is key in this situation.
Increased maternal and fetal risks
Obese pregnant women are at increased risk for many maternal and perinatal complications, and the risks are amplified with increasing degrees of maternal obesity. For this reason, a detailed history and physical examination are critical at the initial obstetrics visit, with ongoing monitoring as needed.
Tables
Antepartum Care |
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Initial obstetrics visit |
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BMI of < 40 kg/m2 |
BMI of ≥40 kg/m2 |
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History and physical examination screening for maternal comorbidities |
Consider maternal echocardiogram, pulmonary function testing, sleep study |
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Laboratory testing |
+/- Thyroid function tests |
Thyroid function tests |
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A1c if not diabetic [24] |
A1c if not diabetic, with GTT as indicated [24] |
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| +/- Hypertension panel for baseline | Hypertension panel for baseline | ||
Ultrasound scan |
First trimester dating/rule out multiples |
First trimester dating/rule out multiples |
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Counseling on weight gain |
11-20 lb total |
< 15 lb and none is acceptable in the setting of excellent nutrition |
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Exercise |
Aerobic activity minimizing high impact |
Walking and swimming (likely best tolerated) |
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Genetic counseling/screening |
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Aneuploidy – no different |
Serum analytes OK |
Serum analytes OK |
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NT can be difficult [13] |
NT very challenging [13] |
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NIPS – may have test failure more commonly |
NIPS may not perform well, especially early |
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Patient counseling regarding screening |
Test performance similar to that in non-obese patients |
Testing performance is compromised by obesity, and this is “dose” based |
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Prenatal care through 24 weeks' gestation |
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Ultrasound scan |
Detailed anatomy scan at 20 weeks |
Detailed anatomy scan at 20 weeks |
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Possible fetal echocardiogram at 24 weeks [16] |
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Weight |
Closely monitor and counsel patient |
Closely monitor and counsel patient |
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Prenatal care at 24-36 weeks' gestation |
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Laboratory testing |
1 hour 50 g Glucola challenge/Hct |
1 hour 50 g Glucola challenge/Hct |
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| Consider hypertension screening for baseline if not already done | |||
Ultrasound scans |
Serially for growth q 4-6 weeks until delivery |
Serially for growth q 3-4 weeks until delivery |
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Frequency of visits for screening (development of complications will require more frequent visits) |
Q 4 weeks until 28-32 weeks, then q 2 weeks until 36 weeks, then q 1-2 weeks until delivery |
Q 4 weeks until 28 weeks, then q 1-2 weeks until 36 weeks, then weekly |
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Weight gain |
Closely monitor and counsel patient |
Closely monitor and counsel patient |
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Antenatal surveillance (NST/AFI) |
For BMI of 35.0-39.9 kg/m2, consider weekly antenatal testing starting at 37 weeks’ gestation |
Consider weekly antenatal testing at 34 weeks |
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Anesthesiology |
Consider anesthesia consult if comorbidities such as OSA are present | Consider anesthesia consult Evaluate labor and delivery unit to see if they have the equipment and staff to handle patient’s size |
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TOLAC counseling |
Per routine for non-obese patients |
Factor in lower success rate with elevated BMI |
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Prenatal care at ≥36 weeks' gestation |
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Antenatal surveillance |
FKC and other only as indicated for non-obese patients if BMI < 35.0 For patients with BMI of 35.0-39.9, consider weekly antenatal testing starting at 37 weeks’ gestation |
Potentially reconsider NST/AFI starting at 36 weeks if not started earlier |
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| Discussion of delivery plan | Per routine for non-obese patients | Consider induction of labor at 39 weeks, if not already delivered Discuss activities to expect if cesarean section needed |
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Delivery/Intrapartum Care |
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Timing of delivery |
By 41.0 weeks but 40 weeks reasonable and even 39 weeks if excellent Bishop score [33] |
Some experts recommend delivery at 39 weeks if not already delivered for comorbidities [33] |
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Anesthesiology |
Consult as indicated for non-obese patients |
Alert them for anesthesia assessment when patient admitted even if not anticipating need for anesthesia services Can assess if regional anesthesia is an option or not |
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Unscheduled cesarean section for indications |
Routine management [39] |
Consider in labor management given the inability to do a truly emergent cesarean section [39] |
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Incision type for cesarean section |
Routine management [19] |
Consider patient body habitus; consider supra-umbilical if large pannus Vertical incision seems to have fewer complications |
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Antibiotic coverage for cesarean section |
Routine management [44] |
Consider increased dose based on weight and consider repeat dose 4 hours post initial dose [44] |
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Postpartum Care |
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DVT prevention |
Similar to non-obese patients [49] |
Consider use of anticoagulation medications, especially if patient has other risk factors for DVT, such as cesarean section, preeclampsia, infection [49] Weight based rather than BMI based is preferred |
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Difficulty with lactation |
Lactation consultation in hospital and after discharge [51] |
Lactation consultation in hospital and after discharge [51] |
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| AFI = amniotic fluid index; BMI = body mass index; DVT = deep vein thrombosis; FKC = fetal kidney circumference; GTT = glucose tolerance test; Hct = hematocrit; NIPS = noninvasive prenatal screening; NST = nonstress test; NT = nuchal translucency; OSA = obstructive sleep apnea; TOLAC = trial of labor after a cesarean section. | |||
