Pregnancy Weight Gain Calculator

On track means you are within the range for this week. Being a little above or below is common from week to week. The overall trend matters most.

At term, a typical gain is made up of the baby (about 3.4 kg), placenta (0.7 kg), amniotic fluid (0.8 kg), larger uterus (1 kg), breast tissue (0.5 kg), extra blood (1.5 kg), extra fluid (1.5 kg) and energy stores (2.5–3.5 kg).

Gaining within your recommended range supports your baby's growth and lowers the chance of some complications. Gaining much less than recommended has been linked with babies being born small; gaining much more has been linked with gestational diabetes, high blood pressure, a larger baby and keeping extra weight after birth. These are associations, not certainties. Many people outside the range have healthy pregnancies, but the range is a useful compass.

The range depends on your BMI before pregnancy, because people who start lighter need to gain more and people who start heavier need to gain less. Use your weight from just before you became pregnant, not your weight at your first appointment.

Singapore uses lower BMI cut-offs for health risk in general (23 and 27.5 rather than 25 and 30), because health risks start at a lower BMI in many Asian people. For pregnancy weight gain, though, the IOM ranges remain the reference, and your doctor may personalise your target.

It's worth paying attention to. A study of more than 900 women at a Singapore maternity hospital found that over a quarter gained more than the IOM range, and starting pregnancy overweight made that more likely.

• You need no extra calories in the first trimester, and only about one healthy snack's worth later on.
• Build meals around vegetables, whole grains, protein (fish low in mercury, eggs, tofu, legumes, lean meat) and calcium-rich foods. At hawker centres, ask for less rice or gravy, add a vegetable side, and choose soups and steamed or grilled dishes more often than fried ones.
• Choose water or kopi/teh kosong over sweet drinks and bubble tea, and keep sweets and fried foods as occasional treats.
• If you're above your range, don't diet. Focus on food quality and gentle activity.
• If you're below it, regular small meals and nourishing snacks help, especially after early nausea.

For most uncomplicated pregnancies, about 150 minutes a week of moderate activity, such as brisk walking, swimming or prenatal classes, is recommended. In Singapore's heat, walk early in the morning or in the evening, or use an air-conditioned mall or gym, and drink plenty of water. Avoid contact sports and activities with a risk of falling, and stop and seek advice if you feel dizzy, short of breath at rest, have chest pain, bleeding or regular painful contractions.

Only part of pregnancy weight gain is your baby. At full term, a typical gain is made up of the baby (around 3.4 kg), the placenta and amniotic fluid (about 1.5 kg), the growing uterus and breast tissue (about 1.5 kg), extra blood and fluid (about 3 kg) and energy stores (about 2.5–3.5 kg) that help with breastfeeding. Seeing it this way can make the numbers feel less personal and more practical.

In the first trimester, a gain of 0.5–2 kg is expected in total. From week 13 to week 40, the calculator spreads the rest of your recommended total evenly across the remaining 27 weeks, which keeps the weekly rate within the IOM guidance for your BMI group. Example for a healthy-weight BMI: the total range is 11.5–16 kg, so by week 20 the recommended gain is about 3.4–5.6 kg, and by week 30 about 7.4–10.8 kg.

For twins, the IOM gives provisional ranges for healthy weight (16.8–24.5 kg), overweight (14.1–22.7 kg) and obese (11.3–19.1 kg) BMI groups; there is no twin guideline for underweight. If you have a medical condition, a history of eating disorders, or are under 18, your care team may set a personal target. Please use theirs.

Your doctor or midwife may weigh you at appointments or ask you to keep track at home. Bring your results. The PDF shows your BMI group, recommended range and current position on one page. If you're outside the range, ask what to focus on: food choices, activity, or simply watching the trend. If you've had an eating disorder or find weighing distressing, say so; you can agree a plan that doesn't involve regular weigh-ins.