More than half the female population of the United States is overweight or obese. Thirty-two percent of women aged 20–39 and 40% of women aged 40–59 are obese.¹ One-third of adolescent females aged 12–19 are overweight and obese, with 20% qualifying as obese.¹ Overweight and obese women are no less likely to be sexually active and therefore at risk of pregnancy than normal-weight women.² Adolescent females in the higher-weight categories have a higher risk of unintended pregnancy than their normal-weight peers due to lower self-esteem and less confidence negotiating condom and contraception use.²

Obesity increases several maternal and fetal risks associated with pregnancy, including gestational diabetes, preeclampsia, fetal macrosomia, emergency cesarean section, and stillbirth. In addition, pregnancy can exacerbate pregestational comorbidities such as hypertension, diabetes, and obesity. Obese women should plan their pregnancies to optimize their health and minimize maternal and fetal complications.

Until recently, however, obese women have been excluded from contraception trials, in which participants are generally limited to within 130% of their ideal body weight.² Therefore, health care providers experience difficulty counseling their obese patients about the safety and efficacy of contraception methods available in the United States.

For the purposes of this chapter, the World Health Organization (WHO) body mass index (BMI) classification system is used.³ A BMI of 30 kg/m² is considered obese (Table 27-1).

The contraception options available in the United States are listed in Table 27-2 along with their pregnancy rates with perfect use (efficacy), typical use (effectiveness), and continuation at 1 year. All methods are more effective than no method. However, as sterilization, intrauterine devices (IUDs), and the subdermal contraceptive implant do not require patient compliance to work properly, their pregnancy rates with typical use approach perfect use pregnancy rates. Both the American Congress of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics recommend intrauterine devices and the subdermal contraceptive implant as first-line contraceptives for women of all ages as they are long-acting, reversible contraceptive (LARC) methods.^4,5 Their effectiveness is as high as that of sterilization without being permanent. The Medical Eligibility Criteria tables produced by the Centers for Disease Control and Prevention (CDC) provide assistance in determining which methods are appropriate for obese patients (Table 27-3). Methods in category 1 do not have any restrictions. Current evidence indicates the benefits of methods in category 2 outweigh the risks. The methods in categories 1 and 2 can be considered safe for otherwise-healthy obese women.⁶

There are three methods of emergency contraception available in the United States: levonorgestrel (LNG), 150 mg orally; ulipristal acetate (UPA), 30 mg orally; and the copper intrauterine device (IUD). LNG is available over the counter in branded and generic forms (Plan B One Step, Next Choice One Dose, Take Action, My Way) and is recommended by the manufacturer to be taken within 72 hours after unprotected intercourse to decrease risk of pregnancy by 88%.⁷ UPA (Ella) requires a prescription. Both can be used up to 150 hours after unprotected intercourse, although UPA has a higher success rate (65% fewer pregnancies at 24 hours to 42% fewer pregnancies at 72 hours) when compared to LNG.

Randomized trials of both LNG and UPA indicated obesity increases the risk of failure for both oral methods. For women using LNG, risk of pregnancy quadrupled in obese (BMI > 30) women when compared to normal-weight or underweight women (odds ratio [OR] 4.41, 95% confidence interval [CI] 2.05, 9.44). Obese women using UPA demonstrated a nonstatistically significant doubled risk of pregnancy (OR 2.62, 95% CI 0.89, 7.00). With regard to weight, these methods ceased to be beneficial at 70 kg for LNG and 88 kg for UPA.⁸ Analysis of phase 3 trials of UPA indicated twice the pregnancy rate of women weighing over 85 kg when compared to women weighing less than 85 kg (3.4% vs. 1.6%).⁹ Of note, few participants in these trials had a BMI above 35 kg/m².

Women in these weight categories should consider a copper IUD (Paragard). The copper IUD is recommended for up to 5 days after unprotected intercourse. Thirty years of data from around the world gives the copper IUD pregnancy rate of 0.09% when used as emergency contraception.¹⁰ Its effectiveness is not affected by weight and has the advantage of providing continued contraception for up to 10 years.

The most effective methods prevent pregnancy over 99% of the time and do not require participation by the user for their high effectiveness.

Sterilization

Permanent sterilization is a highly reliable method of contraception for women confident they have completed childbearing. In the United States, female sterilization is one of the most popular methods of contraception, following oral contraceptives.¹¹ About 10% of women had partners who had undergone vasectomy.¹¹ Vasectomy is highly effective, with an estimated failure rate of 0.15%.¹² This method should be considered as the health and weight of the female patient are not affected. The couple needs to be counseled that vasectomy is not immediately effective, and another method of contraception should be used until semen analysis verifies azospermia. In addition, if the relationship ends, the woman will need another method of contraception.

Female sterilization involves occlusion of the fallopian tubes, whether by laparotomy, minilaparotomy, laparoscopy, or hysteroscopy. Because the mechanism of action involves mechanical occlusion of the fallopian tubes, efficacy should not be affected by weight or obesity. There is no data to support or refute this idea.

Approximately half of female sterilizations occur in the immediate postpartum period with partial salpingectomy.¹¹ After a vaginal delivery, access to the peritoneal cavity through a small umbilical incision may be difficult depending on the patient’s abdominal adipose distribution. Other authors have found the Alexis (Applied Medical, Rancho Santa Margarita, CA) can facilitate visualization of the anatomy.¹³ Distribution of abdominal adipose tissue may impede access to the fallopian tubes during cesarean section regardless of the larger incision. In the event fallopian tubes can be visualized but not safely brought to the incision, Filshie clips are an option. While found to be acceptably effective for interval sterilization, Filshie clips had a statistically significantly higher pregnancy rate after 24 months than partial salpingectomy in a multicenter trial.^11,14 Cumulative pregnancy probability for the clip was 0.017 versus 0.004 in the partial salpingectomy group.

Currently, most abdominal interval female sterilizations are performed laparoscopically. Initial analysis of the Collaborative Review of Sterilization (CREST), a large, multicenter, cohort study from 1978 to 1987, did not factor in BMI or weight in their evaluation of efficacy for each method.¹⁵ A secondary analysis of the data looked at risk factors resulting in increased complications. Obesity was found to be an independent risk factor for complications, OR 1.7 (95% CI 1.2, 2.6). Of the 21 women in whom entrance or pneumoperitoneum could not be achieved, 15 (71%) were obese. Other independent risk factors included diabetes mellitus and previous abdominal or pelvic surgery.¹⁶ However, most of these data were collected in the early years of laparoscopic surgery; technique and instruments have improved, especially due to laparoscopic bariatric surgery, since the mid-1980s when data collection concluded.¹¹ Also, more current data comparing laparoscopic abdominal surgery to laparotomy indicated a 70%–80% reduced risk of infection when using a laparoscopic approach instead of the open approach for obese patients. For this reason, laparoscopic sterilization should be considered over minilaparotomy.¹⁷

Hysteroscopic sterilization offers a means of female sterilization that avoids entering the abdominal cavity, general anesthesia, and their accompanying risks. Essure^® (Bayer Health Pharmaceuticals) is the method of hysteroscopic sterilization available in the United States. Approved in 2002 by the US Food and Drug Administration (FDA), Essure is a nickel-titanium coil microinsert introduced into the fallopian tube ostia hysteroscopically.¹⁸ This stimulates a local tissue reaction, resulting in fallopian tube occlusion within 90 days. The manufacturer recommends occlusion be confirmed by hysterosalpingogram at the end of the 90 days. In the interim, women should use a second method of contraception or abstain from sexual intercourse. About 5% of patients will not experience tubal occlusion at 90 days.¹⁹ While surgeons may have more difficulty accessing the cervix in the office and prefer to perform the procedure in the operating room, data indicate equal sterilization success regardless of BMI or location of procedure.¹⁸

Intrauterine Devices

In the United States, one nonhormonal and three hormonal devices (IUDs) are available. They are all T shaped. The three hormonal IUDs all contain the progestin hormone LNG and include Mirena^®, Skyla^®, and Liletta^TM. The mechanism of action of the LNG IUD includes thickening of cervical mucus to prevent sperm entrance into the uterus, inhibition of capacitation or survival of sperm, and possible prevention of implantation. Mirena contains 52 mg of LNG, releasing 20 μg/d. It is approved for 5 years of use and is FDA approved to manage menorrhagia.²⁰ Skyla is slightly smaller than Mirena and contains 13.5 mg of LNG, releasing 14 μg/d. It is approved for 3 years of use.²¹ Liletta contains 52 mg of LNG, releasing 18.6 μg/d. It is approved for 3 years of use and is the same size as Mirena.²² While neither Skyla nor Liletta has FDA approval to manage menorrhagia, both devices decrease bleeding and can result in amenorrhea (Table 27-4).

The nonhormonal IUD available in the United States is the Paragard^®. It has an exposed surface area of 380 m² of thin copper wire wrapped around a polyethylene frame with barium.²³ It is approved for 10 years of use and does not have any effect on menstrual bleeding after the first few months.

Serum LNG levels have been noted to be lower in obese women using an LNG IUD.²⁴ However, as the mechanisms of action for both the LNG IUD and the copper IUD are local, these methods maintain their efficacy regardless of the patient’s weight. An analysis of Contraceptive CHOICE data demonstrated no difference in failure rate of 1/100 woman-years (WY) between normal-weight, overweight, and obese women.²⁵ In addition, the IUDs do not affect weight, lipid, or glucose metabolism.

Inserting the IUDs may be difficult for obese patients. Ultrasound guidance can be helpful when bimanual exam cannot provide information about uterine size or position. Also, an IUD can be inserted at the time of diagnostic or therapeutic dilation and curettage for patients with abnormal uterine bleeding.

Contraindications to IUD use no longer include nulliparity or adolescence as they did in the past (Table 27-5).