Obesity in Pregnancy

Contributor: Adam Tyson, MD

Last Update: 8/13/2014

 

Obesity in Pregnancy

Obesity is defined as a BMI > 30.0.  It can be further categorized as follows:

• Class I  BMI 30-34.9
• Class II  BMI 35-39.9
• Class III  BMI 40 and greater

According to the National Health and Nutrition Examination Survey (2008), the prevalence of obesity among women in the US was 35.5%.  If overweight women (BMI of 25-29.9) are included with this group the percentage of women in the US swells to 64.1%.  All women should have a BMI calculated at the time of the first prenatal visit based on her height and pre-pregnancy weight.  The initial weight at the first Ob visit can be substituted if necessary.

Preconception Care

If possible, all overweight and obese women should be counseled prior to conception regarding healthy lifestyle choices including weight reduction via diet and exercise.  The goal is a normal BMI (18.5-24.9), although smaller reductions may be helpful as well.  Referral to nutrition services, physical therapy and primary care physicians may be appropriate.

Counseling should also reflect minimization of other modifiable risk factors such as smoking and drug use which may compound the effects of obesity (ie smoking as a risk factor for wound disruption or VTE).  Patients with a BMI > 40 or >35 with a co-morbidity related to obesity are candidates for bariatric surgery and should be offered referral.

Risks of Obesity in Pregnancy

In addition, counseling prior to pregnancy or in early pregnancy should include the increased risks for pregnancy complications.  These increased risks include fetal malformations, gestational diabetes, hypertention, macrosomia, IUFD, need for induction, post-dates pregnancy, operative vaginal delivery, cesarean delivery, venous thrombosis, increased blood loss at surgery, and wound complications.  See tables below.

Antepartum Care for the Obese Patient

• Viability ultrasound to establish EDC
• During initial visit assess for signs/symptoms of chronic illness associated with obesity such as hypertention, diabetes, sleep apnea and hypothyroidism.
• Obesity is a risk factor for adult onset diabetes; therefore, women who have not been screened within the previous 3 years should undergo screening at the time of entry to prenatal care.  Screening options include either a fasting plasma glucose <126 ( not a capillary blood glucose or fingerstick), a Hemoglobin A1C <6.5%, or a one hour  50 gram glucola.   A normal test at this time should be followed by a repeat screening test at 26-28 weeks.
• Because the quality of ultrasound imagers is compromised by obesity, it is difficult to identify structural fetal anomalies as well as “soft markers” for aneuploidy.  First trimester nuchal translucency screening or midtrimester multiple marker screening testing should be strongly encouraged.
• Refer for nutritional counseling at the initial visit with the goal of appropriate weight gain and adequate intake of macro- and micro-nutrients.  The Institute of Medicine recommendations are 11-22 lbs total weight gain in pregnancy; however, recent studies in Category II and III women suggest a lower risk for macrosomia without an increase in SGA, if weight gain is less than the IOM recommendations.
• A targeted anatomic survey (preferably by an MFM physician) should be performed on all obese patients between 20-22 weeks secondary to the increased risk for fetal malformations.
• If fundal height is not easily palpable, serial ultrasounds for fetal growth may be necessary.  At a minimum, EFW should be determined by US between 38-39 weeks gestation due to the increased risk for fetal macrosomia.

Intrapartum Care for the Obese Patient

• Chart an EFW on the hospital H&P (preferably this will be from a 38-39 week US).
• Counsel the patient that she is at risk for a longer labor, increased cesarean rate and slower labor progress.
• Be prepared for shoulder dystocia with positioning and personnel at the time of delivery.
• VBAC is not contraindicated but given the lower success rate and increase in complications should be part of an informed consent process with the patient.  Much of this counseling should be done in the outpatient setting. See the calculator for successful VBAC at www.perinatology.com.
• Be prepared for postpartum hemorrhage which may be increased in obese women.
• Given that external fetal monitoring may be suboptimal, early use of fetal scalp electrodes should be considered.  In addition, if unable to obtain external fetal heart rate tracing, cesarean delivery may be indicated especially if labor is induced or augmented.  An informed consent process should take place regarding the diminished capacity for emergent cesarean delivery of an infant experiencing fetal distress during labor in cases of Class III (BMI>40) obesity.

 

Cesarean Delivery in Obese Women

All operative risks are increased in obese women.

Pre-operative antibiotics should be given within 60 minutes prior to cesarean delivery if possible.  The current recommendation is Cefazolin 3 grams IV.  This is the recommendation for women greater than 100 kg.  If the patient has an anaphylatic reaction to penicillin or cephalosporins, then the regimen is Clindamycin 900 mg IV and Gentamicin 5mg/kg IV (maximum 400 mg).

The rate of wound complication can be as high as 30%.  A standardized approach to the abdominal incision based on evidence based data cannot be made.  The patient’s size, pannus, history of prior surgeries and the speed needed for neonatal delivery must be assessed in making an individual decision for each patient.

Intraoperative considerations include having an appropriate surgical table for heavier patients.  The GHS L&D deliver OR tables can accommodate 500 lbs.  If a >500 lbs patient presents, notify the nursing supervisor ahead of the date of delivery and a larger table can be arranged.  The plastic Alexis retractors are available in various sizes including one sized for minilaparotomy which can be used for tubal ligations.

Closure of subcutaneous tissue > 2 cm deep is of benefit in reducing wound complications.  A rapidly absorbable 2-0 or 3-0 suture such as plain gut or Rapide is preferable for this purpose.  Subcutaneous drains are of no benefit and may increase the rate of wound infection. The optimal method of incision closure has yet to be determined (sutures vs staples).

Obesity is a risk factor for VTE.  The 2008 Guidelines from the American Academy of Chest Physicians recommend mechanical OR pharmacologic prophylaxis after cesarean delivery in patients with any additional risk factors (such as obesity). Furthermore, their guidelines recommend mechanical AND pharmacologic prophylaxis for any post-cesarean patient with more than one risk factor.  Therefore, any obese patient with any additional risk factor (ie smoking, >40 yo, nephritic range proteinuria, central venous catheter, IBS, etc) should be considered a candidate for dual prophylaxis.  These patients should also receive thromboprophylaxis for one week after hospital discharge with Heparin 10,000 units SQ BID.  Patients who are to be scheduled for cesarean delivery should be given the prescription for this in the late 3rd trimester and scheduled for an antenatal visit in the Ob Center to receive instructions in giving the injections.

Postpartum Care of the Obese Patient

• Offer nutritional and exercise counseling.
• Offer referral to primary care physician, if patient does not currently have primary care provider.
• Consider referral to bariatric clinic/ surgeons if appropriate.
• Contraceptive options:  The package insert for Implanon states that the effectiveness in obese women is uncertain.  DMPA and the combination patch may be less effective in obese women. Levonorgestrel containing IUDs offer effective reversible contraception and may have additional benefit in preventing endometrial hyperplasia in obese women.

Pregnancy Following Bariatric Surgery

Evidenced-based guidelines for this topic are limited.  Many patients will still be obese during pregnancy, and the above guidelines will apply.  In addition, depending on the type of procedure performed (adjustable gastric band vs. roux en y gastric bypass) additional measures may be required.  Current recommendations are the pregnancy should be delayed 12-18 months following bariatric surgery to allow for stabilization of weight loss.

These patients are at risk for post-surgical complications and a high degree of suspicion must be maintained in any patient presenting with nausea, vomiting, abdominal pain or other symptoms possibly related to abdominal pathology.  Early consultation with the bariatric or general surgeon should be requested when these symptoms occur.

After gastric bypass surgery, patients should not perform an oral glucose tolerance test as this may precipitate dumping syndrome.  Alternatively fasting and 2 hour postprandial blood sugars values can be assessed.

The following are nutritional recommendations from the GHS Bariatric Surgery Service for pregnant patients who have had weight-loss surgery:

Antepartum

• Maintain bariatric diet of 5 meals daily with 2 oz. protein and 2 oz. fruit/vegetable/starch at each meal.
• Maintain adequate protein intake via protein supplementation of at least 20-30 grams daily in addition to meals.
• Maintain hydration with 80 oz. of fluid daily.
• Avoid caffeinated and carbonated beverages.
• Avoid concentrated sweets.
• Follow up with bariatric RD to ensure adequate nutrition.
• Maintain daily multivitamin intake
• Gastric Bypass
• Optisource 1, 4x daily
• Adjustable Gastric  Band or Sleeve Gastrectomy
• Optisource 1, 4 x daily or
• Prenatal MVI 1 tablet daily + 600-800 mg Calcium Citrate (additional) daily + B12 500 mcg sublingual daily

Postpartum

• Continue with antepartum dietary recommendations and repeat labs.
• May need to increase protein supplementation to 30-40 grams daily.
• Refer to bariatric RD for postpartum visit.

 

Recommended Laboratory Studies

• Vitamin D (25-OH, D2 or D3)
• Vitamin B12 (>350 pg/ml)
• Folate (>7 ng/ml)
• Zinc
• Selenium
• CMP (ensure adequate protein, calcium and electrolyte levels)
• CBC (ensure adequate iron levels)

Check these labs at the initial visit, once every trimester and postpartum.

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References

1. ACCP Evidence-based clinical practice guidelines. Chest 2008.
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12. Stothard Kj, TennantPW, BellR, Rankin J. Maternal overweight and obesity and the risk of congenital anomalies: a systematic review and meta-analysis.  JAMA 2009.
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15. Weiss JL, Malone FD, Emig D et al. Obesity, obstetric complications and cesarean delivery rate: a population-based screening study. Am J obstet Gynecol 2004.
16. Use of prophylactic antibiotics in labor and delivery. Practice Bulletin No. 120. American College of Obstetricians and Gynecologists. Obstet Gynecol 2011;117:1472-83.