ORLANDO – The data with respect to the effects of obesity on the efficacy of contraceptives in adolescents are limited, but the general consensus is that if efficacy is reduced, it isn’t by enough to make a real difference, according to Dr. Alene Toulany.
The effect of obesity is likely to be very small, and studies that have looked at pharmacokinetics in obesity have estimated that body weight accounts for only about 10%-20% of the variability of hormone levels, Dr. Toulany said at the North American Society for Pediatric and Adolescent Gynecology annual meeting.
“We know that this is within the normal range for individuals who are not obese, she said.
Dr. Alene Toulany
The concerns regarding efficacy in obese patients are understandable, as obesity increases the metabolic rate, increases clearance of hepatically metabolized drugs, increases circulating blood volume, and affects the absorption of contraceptive steroids through the adipose tissue, she said, adding that “it makes sense that the serum drug levels may be insufficient to maintain contraceptive effects, but the data are very limited and inconsistent.”
That’s not to say obesity isn’t a concern, added Dr. Toulany, an adolescent medicine specialist at the Hospital for Sick Children, Toronto, and the University of Toronto.
“Without fail, all of us will be seeing patients with obesity,” she said. The rate of adolescent obesity has quadrupled in the last 3 decades, increasing from 5% among those aged 12-19 years in 1980 to more than 20% now. A third are currently overweight or obese.
Further, sexually active obese women, regardless of age, are significantly less likely to use contraception, and obese teens are more likely to engage in risky sexual behaviors than are nonobese teens.
For these reasons, it is important to find the most effective contraceptive method, taking into account other risk factors and the likelihood of compliance, she said, noting that obesity is an independent risk factor for venous thromboembolism (VTE) and that studies suggest the risk is additive in users of estrogen-containing contraceptives.
However, she said, the benefits outweigh the risks of pregnancy in obesity – especially of unintended pregnancy.
The absolute risk of VTE in healthy women of reproductive age is small, and in adolescents it’s even smaller, she explained.
“The presence of risk factors for VTE should be taken into account when we see these youth in our clinics, but we can and should offer estrogen-containing contraceptives as long as there are no other risk factors,” she said.
Contraceptive options in young obese patients include:
• Intrauterine devices. There is no evidence that either copper IUDs or progestin-releasing IUDs have reduced efficacy in obese adolescents.
• Implants. These are highly effective in obese women, and even though the concentrations may be 30%-60% lower in obese women, they do remain above the contraceptive threshold for at least the first 3 years, Dr. Toulany said.
• Depot medroxyprogesterone acetate. There is some concern about weight gain with this injectable progestin-only contraceptive, particularly in those who are already obese, but it remains an option, as the levels do remain above what is needed to prevent ovulation. Interestingly, the persistence of ovulation suppression following discontinuation is different in obese women, and may be prolonged, compared with nonobese women; it is important to counsel patients about this, she said.
“So although randomized, controlled trials report no significant weight gain, we do agree with these observational studies that show that overweight and obese teens gain more weight with Depo-Provera than with oral contraceptives or with no contraceptives,” she said.
• Oral contraceptive pills. Although these may be less effective in obese adolescents, they remain an option and may be the best option in a given patient. Combined oral contraceptives are believed to be generally effective for pregnancy prevention, but “may be less forgiving of imperfect use,” and thus may not be the best choice in those who may have problems with adherence, for example.
The contraceptive patch is probably not a good option, because efficacy may be diminished as a result of absorption through the adipose tissues in those weighing more than 90 kg, Dr .Toulany said. Evidence is insufficient regarding the use of contraceptive rings in obese patients.
Bariatric surgery is increasingly being performed in adolescents, and this raises unique concerns with respect to contraception, Dr. Toulany said.
“We recommend discontinuing estrogen-containing contraceptives 1 month before surgery to reduce the risk of VTE postoperatively,” she said.
After bariatric surgery, those who undergo a restrictive procedure such as gastric banding or a gastric sleeve procedure that reduces the volume of the stomach can use oral contraceptives, but postsurgery vomiting and diarrhea could increase the risk of complications. In those who undergo surgery using a technique that involves a significant malabsorption component, such as Roux-en-Y gastric bypass, nonoral contraceptives are the best option.