Preparing for pregnancy isn’t just about buying prenatal vitamins or cutting back on coffee. One of the most powerful steps a woman can take—long before the positive test—is to optimise her body weight and overall metabolic health. It’s a topic that often gets pushed aside, yet it has lifelong implications for both mother and baby.
We know many women enter pregnancy overweight or obese, and this carries real risks. What’s less widely understood is that trying to 'fix things' once pregnancy has already begun is often too late. Research consistently shows that lifestyle changes made during pregnancy have only modest effects on newborn outcomes. The real window of opportunity is the months—sometimes the year—before conception.
The bigger picture: More than just weight
Some women also live with conditions like polycystic ovary syndrome (PCOS), OR diabetes which can make weight management even more challenging. PCOS often comes with insulin resistance, irregular periods, fertility difficulties and sometimes excess hair growth. When PCOS‑related insulin resistance combines with weight‑related insulin resistance, the effects compound. Addressing these issues before pregnancy can improve fertility, hormonal balance and long‑term health.
Why pre‑pregnancy weight matters
Obesity affects almost every aspect of pregnancy. A large Canadian study of more than 226,000 pregnancies found that higher pre‑pregnancy BMI was linked with increased risks of preeclampsia, gestational diabetes, preterm birth, caesarean delivery, stillbirth, and newborn complications requiring intensive care. Babies born significantly larger than average (macrosomic babies) are also more likely to become children—and later adults—with overweight or obesity. The cycle can repeat across generations.
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At the other end of the spectrum, undernutrition carries its own dangers. Historical studies, including those from the Dutch famine, show that babies exposed to severe calorie deprivation in the womb face higher risks of obesity, diabetes, cardiovascular disease and other chronic conditions later in life—especially when born into a world of plentiful food. Ensuring women enter pregnancy with a healthy, stable nutritional status protects both mother and child.
When should women start preparing?
The timeline depends on individual circumstances. Significant weight concerns may require up to 12 months of gradual, sustainable lifestyle change. Smoking and alcohol ideally should be stopped at least three months before trying to conceive.
Some nutrients need early attention too.
• Folic acid: recommended for at least three months before conception and during early pregnancy.
• Iodine: essential from the very start of fetal development, so supplementation is advised before conception and throughout pregnancy and breastfeeding.
• Caffeine: evidence increasingly supports avoiding it when planning pregnancy, as well as during pregnancy itself.
• Regular intake of iron before and during pregnancy will boost the iron stores and prevent anaemia
Between pregnancies: A chance to reset
Postpartum visits are an ideal time to talk about future pregnancy plans. Fertility can return quickly—especially in the first year after birth if a woman isn’t breastfeeding. Conversations about birth spacing, contraception, emotional readiness and financial planning all matter. The World Health Organization recommends at least 18 months between pregnancies to allow the body to recover and rebuild.
A practical, compassionate approach
Healthy lifestyle discussions shouldn’t be reserved only for women with higher BMI. Weight tends to creep up over the years, and conditions like PCOS can accelerate that trend. Understanding the underlying physiology—not just focusing on the scales—can empower women to make sustainable changes.
There’s no single 'best' diet or exercise plan. What works is anything balanced, nutritious and maintainable. Goals should be realistic and centred on wellbeing rather than a specific number on the scale. Overly restrictive approaches can backfire, increasing stress and the risk of disordered eating.
Support from partners, family and social networks makes a huge difference. Preparing for pregnancy is a team effort, not a solo mission.
Dr Johnson Kuttiyil Joseph is a UK-trained, consultant gynaecologist & laparoscopy surgeon working in Nowra, NSW, Australia.
The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.
