Contraception in Obesity

Obesity (BMI 30 kg/m2 or more) is associated with subfertility, higher pregnancy risk and some reduced effectiveness of certain methods. It also adds venous thromboembolism risk with oestrogen. Most methods can still be used, and weight alone is not a reason to withhold any method.

Assessment. BMI, blood pressure, glucose, lipids, obstructive sleep apnoea, previous bariatric surgery, venous thromboembolism history, smoking, polycystic ovary syndrome, medicines and pregnancy intention.

Effectiveness. No method is contraindicated by weight. Combined hormonal methods may have a slightly higher failure rate at higher weight. The levonorgestrel emergency pill may be less effective at higher BMI. Copper devices and levonorgestrel devices are not affected.

DMPA and weight. Average weight gain on DMPA is about 2 to 3 kg in the first year, with larger gains in adolescents who are already obese.

Pregnancy exclusion. The usual criteria apply; a urine test is reliable regardless of weight.

Eligibility for BMI 30 kg/m2 or more.

Method comparison. Intrauterine devices and implants are first choice. DMPA is acceptable but weight gain should be discussed. Combined methods are used only in patients without other thrombotic risk. The combined patch may be less effective at 90 kg or more.

Additional risks. Obesity with hypertension, diabetes, smoking or age 35 years or more shifts the choice to progestin-only or non-hormonal methods.

Special groups. Postpartum obese women have extra thrombotic risk until 6 weeks. Women with polycystic ovary syndrome benefit from a levonorgestrel device for endometrial protection if cycles are infrequent. After bariatric surgery, oral methods may be poorly absorbed.

Regimen lines.

• Etonogestrel 68 mg rod: 3 years; levonorgestrel two 75 mg rods: 5 years or 3 years by system; backup 7 days if inserted after day 7 of bleeding; no dose change for weight.

• Copper T 380A: up to 12 years; levonorgestrel 52 mg device: 5 years; no backup.

• DMPA 150 mg intramuscularly every 13 weeks, up to 4 weeks late, or 104 mg subcutaneously every 13 weeks, up to 4 weeks late; use the full fixed dose, not weight-adjusted.

• Progestin-only pill: one tablet daily without a break; late window 3 hours for the traditional pill, 12 hours for desogestrel and 24 hours for drospirenone; backup 2 days after a late or missed pill.

• Combined pill with ethinylestradiol 30 micrograms: only in obesity without other risk factors; daily for 21 days with a 7-day break; counsel on symptoms of thrombosis.

• Emergency contraception: the copper T 380A within 5 days is the most effective; if oral, levonorgestrel 1.5 mg within 120 hours, with a double dose considered at higher BMI where the clinician judges it appropriate.

Weight counselling. Offer lifestyle and weight support without making it a condition of any method.

Follow up. Review blood pressure, weight and satisfaction at each visit; reassess the method if BMI changes markedly or new risk factors arise.

Venous thromboembolism. Obesity with a combined method raises risk; leg swelling or chest pain needs urgent assessment and stopping the method.

Weight gain on DMPA. If weight rises by more than 5% in the first 6 months, offer an implant or intrauterine device.

Bleeding. Treat bothersome bleeding with ibuprofen 800 mg three times daily for 5 days after exclusion of pregnancy and pathology.

Insertion difficulties. Palpation of the arm may be harder; use ultrasound for non-palpable implants and consider a longer speculum or ultrasound for intrauterine insertion.

Red flags. Leg swelling, breathlessness, chest pain, severe headache.

Referral and escalation. Refer suspected thromboembolism, severe hypertension and pregnancy for specialist care.