Contraception After Bariatric Surgery

Weight loss after bariatric surgery restores ovulation in many women with obesity-related subfertility, so unplanned pregnancy is common in the first year. Pregnancy during rapid weight loss risks nutritional deficiency, small-for-gestational-age infants and complications from the surgery itself, so conception is delayed for 12 to 18 months after the procedure. Procedures differ in how they affect absorption of oral medicines.

Procedure types.

• Restrictive: adjustable gastric band, sleeve gastrectomy. Absorption of oral medicines is largely preserved.

• Malabsorptive or mixed: Roux-en-Y gastric bypass, biliopancreatic diversion, duodenal switch. Absorption of oral hormones may be reduced, and chronic diarrhoea or vomiting can reduce it further.

Assessment. Type and date of surgery, current BMI, weight trajectory, vomiting or diarrhoea, nutritional deficiencies (iron, vitamin B12, folate, vitamin D, calcium), diabetes, hypertension, venous thromboembolism history, smoking, medicines and pregnancy intention.

Timing of surgery and oestrogen. Major surgery with prolonged immobilisation makes combined methods category 4; a combined method is stopped at least 4 weeks before planned surgery and restarted no earlier than 2 weeks after full mobilisation.

Effectiveness. First-year pregnancies per 100 women with typical use: implants 0.05, intrauterine devices 0.2 to 0.8, injectables 3, combined pills 8.

Eligibility.

Method comparison. Methods that bypass the gut (implants, injectables, intrauterine devices) are first choice after any bariatric procedure. Oral pills are acceptable after restrictive surgery but unreliable after malabsorptive surgery. Condoms are added during rapid weight loss.

Bone health. Bariatric surgery lowers bone density, and DMPA adds to the effect; prefer an implant or intrauterine device, or use DMPA with calcium, vitamin D and bone review.

Special groups. Adolescents after bariatric surgery need long-acting methods. Women with diabetes remission still follow the diabetes eligibility rules until it is confirmed.

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.

• Levonorgestrel 52 mg device: 5 years; copper T 380A: up to 12 years; insertion within 12 days of the start of bleeding or at any time if reasonably not pregnant; 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; backup 7 days if started after day 7 of bleeding.

• Oral pills after restrictive surgery: one tablet daily; vomiting within 2 hours means another pill is taken; vomiting or diarrhoea lasting more than 2 days counts as 3 or more missed pills, with backup 7 days.

• Emergency contraception: copper T 380A within 5 days is preferred after malabsorptive surgery; oral levonorgestrel 1.5 mg within 120 hours is used only if no device is available.

Preconception. Delay conception for 12 to 18 months after surgery, correct deficiencies, continue a multivitamin with folic acid 400 micrograms daily (higher doses where advised), and review weight stability before stopping contraception.

Follow up. Review at bariatric clinic visits: weight, nutrition, bleeding, method and pregnancy intention.

Contraceptive failure. Pregnancy after malabsorptive surgery with an oral method is the commonest failure; test early, exclude ectopic pregnancy and refer for nutritional and obstetric review.

Gastrointestinal upset. Persistent vomiting or diarrhoea means oral methods cannot be relied on; switch to a long-acting method.

Thrombosis. Leg swelling or chest pain after surgery is an emergency, and combined methods are stopped.

Bleeding. Treat bothersome bleeding with ibuprofen only if surgical advice allows, because NSAIDs raise ulcer risk after bypass; otherwise use tranexamic acid 500 mg three times daily for 5 days if thrombosis risk is low.

Red flags. Persistent vomiting, severe abdominal pain, leg swelling, heavy bleeding.

Referral and escalation. Refer pregnancy, suspected thromboembolism and nutritional failure to the bariatric and obstetric teams.