Contraception in overweight adolescents

Hormonal contraceptives rank among the most reliable methods of contraception – even for adolescents. When being prescribed for the first time, contraindications as well as risk factors, such as a high body mass index (BMI), should always be kept in mind, as Dr. med. Katarina Sedlecky, Head of the Family Planning Centre at the Health Institute for Mother and Child in Belgrade, Serbia, explains in the interview below.

Dr. Sedlecky, how do hormonal contraceptives and weight affect the risk of venous thromoembolism (VTE)?

K. Sedlecky: Venous thromboembolisms (VTE) are rare in women of reproductive age. A BMI > 30kg/m² triples the risk of VTE and, in combination with combined hormonal contraceptives, the VTE risk is further increased. However, the likelihood of thrombosis in adolescents is very low due to their young age. Excess weight is ultimately only a relative contraindication for the pill. If obesity is the only risk factor, all hormonal contraceptives may be prescribed for teenagers and young women while weighing up the benefits and risks. Caution is advised only if there are other risk factors, such as smoking or advanced age.¹

Adolescents usually prefer a combined pill to a progestin-only product for contraception, primarily because of the cycle control that is generally better and the additional benefits for skin, hirsutism and PCOS. Are there differences among the various combined pills in terms of the VTE risk?

K. Sedlecky: Yes. The increase in the VTE risk under hormonal contraception also depends somewhat on the type of progestin contained in the pill. It appears to be the case that combined contraceptives containing levonorgestrel, norethisterone, and norgestimate have the lowest VTE risk. However, shown in absolute numbers of combined contraceptive users with VTE the differences between various pills are minimal.

What is the situation with regard to efficacy? Is the pill less effective in obese women due to their larger proportion of fatty tissue than in normal-weight women?

K. Sedlecky: The fatty tissue amount does indeed affect the hormone pharmacokinetics. This means that severely overweight women more commonly have fertility problems than women of normal weight. In addition, a study has shown: women with a BMI > 35 kg/m² who take a contraceptive pill containing 30µg ethinylestradiol (EE) and 150µg levonorgestrel (LNG) do not achieve the same high oestrogen peak plasma levels as normal-weight women. LNG peak levels are also lower in obese women. In contrast to ethinylestradiol peak levels, however, the difference is not significant when compared to patients with a lower BMI^.2

Based on existing data to date, it is not possible to say for certain that overweight women using combined hormonal contraception are generally less well protected and become pregnant more often than women of normal weight. Conversely, however, it is also not possible to completely rule out the fact that contraception may be less reliable in some individual cases, as studies have shown that there are sometimes considerable differences between women.

How about the vaginal ring and patch?

K. Sedlecky: Etonogestrel levels are similar in obese and normal-weight women using a vaginal ring for contraception. Although ethinylestradiol levels are lower in women with a high BMI than in women with a normal BMI, they are still within the therapeutic range. Therefore, there does not appear to be reduced efficacy in severely obese women who use a vaginal ring for contraception.³ Unlike the patch: There are indications that the contraceptive patch is less effective in women with a BMI > 30 kg/m² or with a body weight of more than 90 kg.

Does weight also affect the efficacy of the intrauterine system (IUS)?

K. Sedlecky: Yes, however, there is only a slight difference in the plasma levels of obese and normal-weight women using the levonorgestrel IUS as a contraceptive. It is therefore more effective than the pill in women with a very high BMI.⁴ Furthermore, because the IUS only acts locally in the womb, it does not increase the VTE risk. What’s more, it only has a minimal effect on plasma lipids and glucose metabolism and protects the endometrium which is very important because obese women are at higher risk for endometrial cancer. Like the copper intrauterine device (IUD), it is therefore also a very good method of contraception for severely overweight patients.⁵

What conclusions may be drawn from this knowledge for practice?

K. Sedlecky: The failure rate of the combined pill in women with a BMI > 35 kg/m² may be somewhat higher than in normal-weight women due to the larger mass of fatty tissue. If severely overweight women still wish to use the contraceptive pill, experts recommend prescribing a product that contains 30µg ethinylestradiol. If a lower-dose pill is used, a continuous intake is primarily recommended instead of the 21/7 regimen. In my opinion, patients should also always be advised about alternative and reliable methods of contraception. These include both progestin-only products as well as coils. Copper coils are strongly recommended for severely overweight and obese women. However, the levonorgestrel-IUS is also reliable for women with a high BMI and is of particular benefit to women with hypermenorrhea.⁵

Are there also recommendations for emergency contraception in obese women?

K. Sedlecky: Yes. In obese women at high risk for an unwanted pregnancy, the copper coil is recommended firstly and emergency contraception with ulipristal acetate secondly and, if this is not possible, levonorgestrel. Copper coils and ulipristal acetate may be used for up to 120 hours after unprotected intercourse, levonorgestrel for up to 72 hours.⁵

What methods of contraception are effective after bariatric surgery?

K. Sedlecky: Oral hormonal contraceptives appear to be less effective after bariatric surgery, particularly in the case of post-surgical malabsorption.⁵ However, if there is no malabsorption there is no reason why the pill cannot
be used as contraception following
bariatric surgery, provided that the
VTE risk and contraindications are
taken into consideration. Other hormone products, such as the IUD and injection, are also effective following gastric
surgery.^6,7

The interview was conducted by Claudia Benetti