Weight, metabolic health, fertility and pregnancy are closely linked. Improving health before pregnancy, before IVF, during pregnancy and between pregnancies can significantly improve outcomes for both mother and baby.

Obesity is not a personal failure. It is a chronic, complex medical condition influenced by hormones, metabolism, genetics, sleep, stress, mental health and environment.

Obesity during pregnancy can affect both the mother and baby. It increases the risk of complications during pregnancy, birth and later life for both generations.

• Gestational diabetes
• High blood pressure
• Pre-eclampsia
• Caesarean section
• Blood clots
• Sleep apnoea

• Higher birth weight, or macrosomia
• Birth complications
• Low blood sugar after birth
• Increased risk of childhood obesity
• Future risk of diabetes and metabolic disease

Obesity is a chronic and multifactorial medical condition. It can be influenced by genetics, hormones, metabolism, sleep, stress, mental health, environment and lifestyle.

Many women experience stigma or judgement regarding weight, fertility or pregnancy. Treatment should focus on health optimisation, safety and long-term support.

How Weight Affects Fertility

Excess weight can reduce fertility in both natural conception and assisted reproduction.

• Irregular ovulation
• Reduced fertility
• Higher miscarriage rates
• Hormonal imbalance

Even modest weight loss of 5–10%of body weight may help restore ovulation, improve menstrual regularity, increase fertility and improve pregnancy outcomes.

Polycystic ovarian syndrome, or PCOS, is closely linked with obesity and insulin resistance.

• Irregular periods
• Difficulty conceiving
• Increased miscarriage risk
• Insulin resistance
• Weight gain

Weight management and metabolic health optimisation may improve ovulation, hormonal balance, fertility and pregnancy outcomes.

Obesity may reduce the success rates of IVF, ovulation induction and fertility treatment.

Women living with obesity may require higher medication doses, more IVF cycles and longer treatment duration.

Improving metabolic health before IVF may improve outcomes for both mother and baby.

Safe Weight Management Before Pregnancy

A healthy pre-pregnancy plan may include nutritional support, physical activity, sleep optimisation, stress management, smoking cessation, medication review and folic acid supplementation.

For some women, bariatric surgery may be considered. Pregnancy is usually not recommended for 12–18 months after bariatric surgery, while weight stabilises and nutritional health is optimised.

Many women experience improved fertility and safer pregnancies after bariatric surgery. However, pregnancy requires careful planning and follow-up.

• Delay pregnancy for 12–18 months where possible
• Nutritional monitoring
• Vitamin supplementation
• Specialist antenatal care
  Follow-up with bariatric team, GP, obstetrician and dietitian

Injectable weight loss medications such as Ozempic®, Wegovy® and Mounjaro® are increasingly used for obesity management. However, they are not currently considered safe during pregnancy.

When should these medications be stopped?

• Stop injectable weight loss medications at least 2 months before trying to conceive
• Use reliable contraception while taking them
• Discuss pregnancy planning with your doctor before stopping treatment

If pregnancy occurs unexpectedly while taking these medications, stop the medication and contact your GP, obstetrician, fertility specialist or surgeon promptly.

Current guidelines suggest women with obesity gain approximately 5–9 kg during pregnancy. However, every woman is different.

Starting BMI, diabetes risk, blood pressure, previous pregnancy complications and overall metabolic health may influence what is appropriate.

The safest and most effective management includes healthy eating, nutritional counselling, moderate exercise, monitoring weight gain, screening for gestational diabetes and regular antenatal care.

Exercise is safe in most uncomplicated pregnancies and may reduce the risk of gestational diabetes.

Weight retained after pregnancy can increase the risk of type 2 diabetes, heart disease and future pregnancy complications.

Good postpartum care may include weight management support, breastfeeding support, safe contraception advice and planning future pregnancies safely.

Managing obesity, fertility, IVF and pregnancy works best with a multidisciplinary team, which may include obstetricians, fertility specialists, bariatric surgeons, dietitians, endocrinologists, physiotherapists, midwives and anaesthetists.

• Obesity can affect fertility, IVF success, pregnancy and long-term health
• Even modest weight loss before pregnancy can improve fertility and outcomes
• Weight management before IVF may improve treatment success
• PCOS symptoms and fertility may improve with metabolic health optimisation
• Exercise is safe in most uncomplicated pregnancies
• Injectable weight loss medications should be stopped at least 2 months before pregnancy
• Pregnancy is usually delayed for 12–18 months after bariatric surgery
• Postpartum weight management is important for future pregnancies and long-term health