The NHS and NICE (National Institute for Health and Care Excellence) base pregnancy weight gain recommendations on your pre-pregnancy BMI. Gaining the right amount of weight helps your baby grow healthily while reducing risks for both mother and child.
| Pre-pregnancy BMI | Category | Recommended Gain (kg) | Recommended Gain (lbs) |
|---|---|---|---|
| Under 18.5 | Underweight | 12.7–18.1 kg | 28–40 lbs |
| 18.5–24.9 | Normal weight | 11.3–15.9 kg | 25–35 lbs |
| 25.0–29.9 | Overweight | 6.8–11.3 kg | 15–25 lbs |
| 30.0 and above | Obese | 5.0–9.1 kg | 11–20 lbs |
| Any (twins) | Twin pregnancy | 15.9–20.4 kg+ | 35–45 lbs+ |
Many women wonder where pregnancy weight actually goes. Here is a typical breakdown for a normal-weight woman gaining around 12.5 kg:
Weight gain is not evenly spread across pregnancy. The pattern matters as much as the total.
Total weight gain of just 1–2 kg is normal in the first trimester. The embryo is tiny, and much of the discomfort from nausea or morning sickness can actually make eating difficult. Some women lose a small amount of weight during this period, which is generally not a concern provided weight gain picks up in the second trimester.
This is typically when appetite returns and weight gain accelerates. For normal-weight women, approximately 0.45 kg (1 lb) per week is typical. This is when the baby grows most rapidly and when you may first notice your bump becoming visible.
Weight gain continues at a similar pace — roughly 0.45–0.5 kg per week. The baby is laying down fat stores, and your blood volume continues to increase. In the final 2–3 weeks, some women find their weight plateaus or even drops slightly as the baby drops into the pelvis.
Carrying twins requires significantly higher calorie intake and results in greater weight gain. The NHS and NICE guidelines for twin pregnancies are:
If you are expecting twins, you will be referred to a consultant obstetrician and will receive more frequent antenatal appointments to monitor weight and fetal growth.
Contact your midwife or GP if:
Last updated: February 2026. This calculator provides general guidance only and does not replace professional medical advice. Always consult your midwife or GP for personalised recommendations. Written by Mustafa Bilgic.
Pregnancy is an exciting time, and being well-informed helps you prepare for every stage. The NHS provides comprehensive free maternity care throughout pregnancy, including regular check-ups, scans, and specialist support where needed.
Your first appointment with a midwife, known as the booking appointment, usually happens between 8 and 12 weeks. You will receive a dating scan at around 12 weeks and an anomaly scan at around 20 weeks. Throughout your pregnancy, regular appointments monitor both your health and your baby's development.
This calculator helps you track important dates and milestones throughout your pregnancy. All information is based on NHS guidelines and standard pregnancy timelines. For specific medical advice, always consult your midwife or GP.
Data verified against official UK government sources. Last checked April 2026.