Enter your height, pre-pregnancy weight and week of pregnancy to see the recommended weight gain so far and by the time of birth.
Recommended weight gain depends on your pre-pregnancy body mass index (BMI). The US Institute of Medicine (IOM) recommendations and the table in the Turkish Ministry of Health antenatal care guideline give the same values (IOM, 2009; Turkish Ministry of Health, 2026):
| Pre-pregnancy BMI | Total gain | Weekly gain in 2nd and 3rd trimesters: mean (range) |
|---|---|---|
| Underweight (<18.5) | 12.5–18 kg (28–40 lb) | 0.51 (0.44–0.58) kg; 1 (1–1.3) lb |
| Normal weight (18.5–24.9) | 11.5–16 kg (25–35 lb) | 0.42 (0.35–0.50) kg; 1 (0.8–1) lb |
| Overweight (25.0–29.9) | 7–11.5 kg (15–25 lb) | 0.28 (0.23–0.33) kg; 0.6 (0.5–0.7) lb |
| Obese (30.0 or more) | 5–9 kg (11–20 lb) | 0.22 (0.17–0.27) kg; 0.5 (0.4–0.6) lb |
The Turkish Ministry of Health guideline recommends referral to a dietitian when BMI is below 18.5 or 30 and above. If you do not know your pre-pregnancy BMI, start with the BMI calculator.
Gain in the first trimester is small: people typically gain about 1–2 kg in this period, and the IOM calculations assume 0.5–2 kg (1.1–4.4 lb) in the first trimester. The recommended weekly gain applies from the second trimester and is assumed to be steady until birth (IOM, 2009).
The Turkish Ministry of Health guideline also gives a monthly upper limit: no more than 2 kg a month for underweight and normal-weight people, and no more than 1 kg a month for those who are overweight or obese (Turkish Ministry of Health, 2026). In the IOM table, the mean weekly gain in the second and third trimesters is 0.42 kg for normal-weight women (IOM, 2009). These two recommendations are expressed differently and do not match exactly; discuss your own goal with your doctor at your checkups.
The tool calculates your pre-pregnancy BMI, sets your category from the one-decimal value shown on screen and shows the total and weekly ranges from the chart. For the expected gain it assumes a total of 0.5–2 kg over the first trimester (up to week 13); from week 14 it adds your category's weekly range for each week and caps the result at the total range in the chart, adding nothing after week 40. It also shows an approximate further gain, calculated by multiplying the number of weeks left until week 40 by your category's weekly range; up to week 13 it uses weeks 14–40 (27 weeks) and leaves out the 0.5–2 kg of the first trimester. This figure is not based on your actual weight and is not shown from week 40 onwards. Up to week 13, the expected weight shown is for the end of the first trimester. The result is an approximate band, not a target; in the final weeks, the total range in the chart is what counts.
To track your weight week by week, use the weight tracking chart.
NICE, the UK national guideline body, states that evidence on the optimal total weight change in pregnancy, or the change in each trimester, is lacking. It focuses advice on healthy eating and physical activity and does not recommend routine weighing throughout pregnancy unless there is a clinical reason such as gestational diabetes. Height, weight and BMI are measured at booking, and gestational diabetes testing is offered when BMI is 30 or above (NICE NG247, 2025).
The Turkish Ministry of Health guideline, by contrast, asks for weight gain to be checked against the chart at antenatal visits. Whichever approach is followed, pregnancy complications are more common at the upper and lower extremes of both BMI and weight gain (UpToDate, 2026).
Your weight gain is reviewed at your checkups. However, sudden and rapid weight gain (for example, more than 2.3 kg [5 lb] a week) and swelling of the face are more common in people who develop preeclampsia and need assessment; in that case, do not wait for your next appointment. Many pregnant people have swelling of the hands and legs without preeclampsia (UpToDate, 2026).
Also seek care without waiting for your next appointment if you have any of the following (Turkish Ministry of Health, 2026):
The NHS advises calling immediately if your baby's movements slow down, stop or change pattern, without waiting until the next day, even in the middle of the night.
Gain in the first three months is small, typically about 1–2 kg. Steady weekly gain starts in the second trimester and continues until birth (IOM, 2009).
The Turkish Ministry of Health guideline gives a monthly upper limit: no more than 2 kg a month for underweight and normal-weight people and no more than 1 kg a month for those who are overweight or obese (Turkish Ministry of Health, 2026). In the IOM table, the mean weekly gain in the second and third trimesters is 0.42 kg for normal-weight women (IOM, 2009). These two recommendations are expressed differently and do not match exactly; discuss your own goal with your doctor at your checkups.
With a pre-pregnancy BMI of 18.5–24.9, the recommended total gain is 11.5–16 kg (25–35 lb) (IOM, 2009; Turkish Ministry of Health, 2026).
The IOM's provisional guidance is 17–25 kg for normal weight, 14–23 kg for overweight and 11–19 kg for obese women. There are not enough data for underweight women; this calculator is for singleton pregnancies.
The safety of intentional weight loss in pregnancy has not been established. The recommended total gain for obese women is 5–9 kg; plan your diet with your doctor and a dietitian.
Pregnancy complications are more common at the lower and upper extremes of weight gain. If you are outside the range, your doctor will also consider weighing errors, swelling and your baby's growth before advising a change (IOM, 2009).
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