Clinical Review

Obesity in pregnancy: Risks and interventions by gestational stage

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

Gestational diabetes, preeclampsia, prolonged hospitalization—these are just a few of the complications that may affect obese gravidas. Here, the authors present a rundown of what to look for when treating this unique population.

PDF Download

References

1. Lu GC, Rouse DJ, DeBard M, Cliver S, Kimberlin D, Hauth JC. The effect of the increasing prevalence of maternal obesity on perinatal morbidity. Obstet Gynecol. 2001;185:845-849.

2. Mokdad AH, Serdula MK, Dietz WH, Bowman BA, Marks JS, Koplan JP. The spread of the obesity epidemic in the United States 1991-1998. JAMA. 1999;282:1519-1522.

3. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report. Bethesda, Md: National Heart, Lung, and Blood Institute; June 1998;1-226.

4. American College of Obstetricians and Gynecologists. ACOG Education Bulletin #229: nutrition and women. Washington, DC: ACOG; 1996.

5. Institute of Medicine subcommittee on nutritional status and weight gain during pregnancy. Nutrition During Pregnancy. Washington, DC: National Academy Press; 1990.

6. Cogswell ME, Serdula MK, Hungerford DW, Yip R. Gestational weight gain among average-weight and overweight women—what is excessive? Am J Obstet Gynecol. 1995;172:705-712.

7. Edwards LE, Hellerstedt WL, Alton IR, Story M, Himes JH. Pregnancy complications and birth outcomes in obese and normal weight women: effects of gestational weight change. Obstet Gynecol. 1996;87:389-394.

8. Parker JD, Abrams B. Prenatal weight gain advice: an examination of the recent prenatal weight gain recommendations of the Institute of Medicine. Obstet Gynecol. 1992;79:664-669.

9. Isaacs JD, Magann EF, Martin RW, Chauhan SP, Morrison JC. Obstetric challenges of massive obesity complicating pregnancy. J Perinatol. 1994;14:10-14.

10. American College of Obstetricians and Gynecologists. ACOG Technical Bulletin #200: diabetes and pregnancy. Washington, DC: ACOG; 2000.

11. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin #29: chronic hypertension in pregnancy. Washington, DC: ACOG; 2001.

12. Baeten JM, Bukusi EA, Lambe M. Pregnancy complications and outcomes among overweight and obese nulliparous women. Am J Public Health. 2001;91:436-440.

13. Stone JL, Lockwood CJ, Berkowitz GS, Alvarez M, Lapinski R, Berkowitz RL. Risk factors for preeclampsia. Obstet Gynecol. 1994;83:357-361.

14. Knight M, Duley L, Henderson-Smart D, et al. The effectiveness and safety of antiplatelet agents for the prevention and treatment of preeclampsia. In: The Cochrane Library, Issue 4, 2000. Oxford: Update Software. Search date 1999. Primary sources: Cochrane Pregnancy and Childbirth Group Trials Register, conference proceedings.

15. Atallah AN, Hofmeyr GJ, Duley L. Calcium supplementation during pregnancy to prevent hypertensive disorders and related adverse outcomes. In: The Cochrane Library, Issue 4, 2000. Oxford: Updated Software. Search date 2000. Primary sources: Cochrane Pregnancy and Childbirth Group Trials Register.

16. Maeder EC, Barno A, Mecklenburg F. Obesity: a maternal high-risk factor. Obstet Gynecol. 1975;45:669-671.

17. Cnattingius S, Bergstrom R, Lipworth L, Kramer MS. Prepregnancy weight and the risk of adverse pregnancy outcomes. N Engl J Med. 1998;338:147-152.

18. Huang DY, Usher RH, Kramer MS, Yang H, Morin L, Fretts RC. Determinants of unexplained antepartum fetal death. Obstet Gynecol. 2000;95:215-221.

19. Gross T, Sokol RJ, King KC. Obesity in pregnancy: risks and outcome. Obstet Gynecol. 1980;56:446-450.

20. Ekblad U, Grenman S. Maternal weight, weight gain during pregnancy and pregnancy outcome. Int J Gynecol Obstet. 1992;39:277-283.

21. Kaiser PS, Kirby RS. Obesity as a risk factor for cesarean in a low risk population. Obstet Gynecol. 2001;97:39-43.

22. Chauhan SP, Magann EF, Carroll CS, Barrilleaux PS, Scardo JA, Martin JN. Mode of delivery for the morbidly obese with prior cesarean delivery: vaginal versus repeat cesarean section. Am J Obstet Gynecol. 2001;185:349-354.

23. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin #5: vaginal birth after previous cesarean delivery. Washington, DC: ACOG; 2000.

24. Grobman WA, Peaceman AM, Socol ML. Cost-effectiveness of elective cesarean delivery after one prior low transverse cesarean. Obstet Gynecol. 2000;95:745-751.

25. Hood DD, Dewan DM. Anesthetic and obstetric outcome in morbidly obese parturients. Anesthesiology. 1993;79:1210-1218.

26. Naef RW, Chauhan SP, Chevalier SP, Roberts WE, Meydrech EF, Morrison JC. Prediction of hemorrhage at cesarean delivery. Obstet Gynecol. 1994;83:923-926.

27. Edwards LE, Dickes WF, Alton IR, Hakanson EY. Pregnancy in the massively obese: course, outcome, and obesity prognosis of the infant. Am J Obstet Gynecol. 1978;131:479-483.

28. Pelle H, Jepsen OB, Larsen SO, et al. Wound infection after cesarean section. Infect Control. 1986;7:456-461.

29. Nielsen TF, Hokegard K. Postoperative cesarean section morbidity: a prospective study. Am J Obstet Gynecol. 1983;146:911-916.

30. Johnson SR, Kolberg BH, Varner MW, Railsback LD. Maternal obesity and pregnancy. Surg Gynecol Obstet. 1987;164:431-437.

31. Vermillion ST, Lamoutte C, Soper DE, Verdeja A. Wound infection after cesarean: effect of subcutaneous tissue thickness. Obstet Gynecol. 2000;95:923-926.

32. Naumann RW, Hauth JC, Owen J, Hodgkins PM, Lincoln T. Subcutaneous tissue approximation in relation to wound disruption after cesarean delivery in obese women. Obstet Gynecol. 1995;85:412-416.

33. Allaire AD, Fisch J, McMahon MJ. Subcutaneous drain vs suture in obese women undergoing cesarean delivery. J Reprod Med. 2000;45:327-331.

34. Wolfe HM, Gross TL, Sokol RJ, Bottoms SF, Thompson KL. Determinants of morbidity in obese women delivered by cesarean. Obstet Gynecol. 1998;71:691-696.

35. Perlow JH, Morgan MA, Montgomery D, Towers CV, Porto M. Perinatal outcome in pregnancy complicated by massive obesity. Am J Obstet Gynecol. 1992;167:958-962.

36. Garbaciak JA, Jr, Richter M, Miller S, Barton JJ. Maternal weight and pregnancy complications. Obstet Gynecol. 1985;152:238-245.

37. Kumari AS. Pregnancy outcome in women with morbid obesity. Int J Gynecol Obstet. 2001;73:101-107.

38. Steinfeld JD, Valentine S, Lerer T, Ingardia CJ, Wax JR, Curry SL. Obesity-related complications of pregnancy vary by race. J Matern Fetal Med. 2000;9:238-241.

39. Jensen H, Agger AO, Rasmussen KL. The influence of prepregnancy body mass index on labor complications. Acta Obstet Gynecol Scand. 1999;78:799-802.

40. Ranta P, Jouppila P, Spalding M, Jouppila R. The effect of maternal obesity on labour and labour pain. Anaesthesia. 1995;50:322-326.

41. Pongthai S. Labour and delivery of obese parturients. J Med Assoc Thai. 1990;73:52-56.

KEY POINTS

All obese patients have an increased risk of gestational diabetes and preeclampsia.
Deep venous thrombosis and its complications—which include maternal mortality—are seen more frequently in the obese patient.
Obesity is associated with an increased likelihood of induction of labor and cesarean delivery.
Obesity is a specific risk factor for several operative complications, including hemorrhage during surgery, postoperative wound infections, aspiration, and pulmonary embolism.

Specific interventions can help reduce the complications associated with obesity in pregnancy, provided physicians remain vigilant in applying the appropriate preventive measures.

Since one third of American women of childbearing age are overweight, obesity clearly has a major impact on the health of pregnant patients. And, as in the general population, the prevalence of this condition is escalating among gravidas. A 2001 study cited a 20% increase in mean maternal weights between 1980 and 1999.¹

In the United States, the prevalence of obesity leaped from 12% to 17.9% between 1991 and 1998.² Even more alarmingly, each year in this country, 280,000 adult deaths are attributable to obesity.

As health-care providers, it is imperative that we understand the impact this epidemic has on pregnancy and delivery so that we can work to minimize related complications.

What is obesity?

There is no single definition of obesity. In obstetric literature, it has been defined as a maternal weight of more than 90 kg (200 lb), more than 114 kg (250 lb), more than 135 kg (300 lb), and anywhere from 50% to 120% above ideal body weight.

In recent years, clinicians have usually determined obesity according to the body mass index (BMI), a simple mathematical formula (weight in kilograms divided by height in square meters) that correlates height and weight with body fat. This method offers several advantages over a basic weight measurement. For one, weight alone does not correlate well with body fat content; BMI, on the other hand, has a 0.7 to 0.8 correlation. In addition, this definition of obesity correlates with morbidity and mortality.³

Using BMI, the Institute of Medicine developed 4 body-type categories⁴:

under 19.8: lean
19.8 to 26.0: normal
26.1 to 29: overweight
over 29: obese

In obstetric patients, BMI is calculated using prepregnancy weight. While the varying definitions of obesity make it difficult to compare and interpret research findings, it is important to note that adverse obstetric outcomes are associated with each classification. The Institute of Medicine also made recommendations on how much weight women in each category should gain during pregnancy⁵:

lean women: 28 lb to 40 lb
normal-weight women: 25 lb to 35 lb
overweight women: 15 lb to 25 lb
obese women: 15 lb or more

While no upper weight-gain limit was set for obese patients, 3 studies recommend 37 lb; researchers found that obese women who gain more than this have increased risk of cesarean delivery and large-for-gestational-age infants.^6-8

Preconception: Control hypertension and diabetes

The negative impact that excess weight has on pregnancy begins even before conception (TABLE 1). For example, obese women are more likely to have chronic hypertension and diabetes. In 1 study, researchers reported the incidence of chronic hypertension among obese patients (defined as those weighing 300 lb or more) to be 33%, compared with 5% among controls, while diabetes occurred in 15% of obese patients and 3% of controls.⁹

Through preconception counseling and management, practitioners can improve pregnancy outcomes among patients with these medical complications. Strict glucose control of pregestational diabetes, for example, decreases the risk of congenital malformations. The 4-fold increase in malformations related to poor glucose control during embryogenesis is diminished if preconceptional glycosylated hemoglobin levels are in the normal range.¹⁰

Note that hypertension may be falsely diagnosed in an obese woman if an inappropriately small cuff is used. When taking the blood pressure (BP) of these patients, therefore, clinicians should make sure the length of the cuff is 1.5 times the upper arm circumference or that the inflatable bladder of the cuff encircles at least 80% of the arm.¹¹ For women with an arm circumference of more than 41 cm, use a thigh cuff to ensure an accurate measurement.

In general, any hypertensive woman of childbearing age should take only agents with documented fetal safety. Drugs such as angiotensin-converting enzyme inhibitors should not be used due to their association with oligohydramnios, fetal hypocalvaria, and neonatal renal failure.

TABLE 1

Obstetric concerns among obese patients

Preconception	Pregestational diabetes mellitus
Preconception	Chronic hypertension
Antepartum period	Gestational diabetes
	Preeclampsia
	Deep venous thrombosis
	Stillbirth
Intrapartum period	Induction
	Cesarean delivery
	Poor VBAC success
	Macrosomia
Postpartum period	Prolonged hospitalization
	Cesarean complications
	Wound infection
VBAC = vaginal birth after cesarean

Antepartum

Gestational diabetes and preeclampsia. During pregnancy, all obese patients—even those without a history of hypertension or diabetes—have an increased risk of gestational diabetes and preeclampsia. Baeten et al¹² recently reported the odds ratios for gestational diabetes, preeclampsia, and eclampsia in the obese nulliparous patient as 5.2, 3.3, and 3.0, respectively.