See your recommended total weight gain range based on your pre-pregnancy BMI, and roughly how much you'd be expected to have gained by your current week.
| Pre-pregnancy BMI | Singleton | Twins |
|---|---|---|
| Underweight (<18.5) | 28–40 lb (12.7–18.1 kg) | Not established |
| Normal (18.5–24.9) | 25–35 lb (11.3–15.9 kg) | 37–54 lb (16.8–24.5 kg) |
| Overweight (25–29.9) | 15–25 lb (6.8–11.3 kg) | 31–50 lb (14.1–22.7 kg) |
| Obese (30+) | 11–20 lb (5.0–9.1 kg) | 25–42 lb (11.3–19.1 kg) |
It depends mainly on your pre-pregnancy BMI: roughly 25–35 lb (11.3–15.9 kg) total is typical for a "normal" BMI carrying one baby, with higher recommended ranges for underweight and lower ranges for overweight or obese pre-pregnancy BMI, per IOM guidelines.
Recommended ranges shift accordingly — underweight pre-pregnancy generally means a higher recommended gain (28–40 lb / 12.7–18.1 kg) to support healthy fetal growth, while overweight or obese pre-pregnancy generally means a lower recommended range (11–25 lb / 5.0–11.3 kg), since more pre-existing reserves are already available.
Yes — twin pregnancies have their own, higher recommended ranges (see the table above), and there isn't enough research to set an established range for an underweight pre-pregnancy BMI carrying twins, so that combination is best discussed directly with your provider.
A single week outside the expected pace usually isn't a concern on its own — gain is rarely perfectly even week to week, and morning sickness, appetite changes and activity levels all play a role. A consistent, sustained pattern of gaining much faster or slower than expected is worth discussing with your OB or midwife.
They're based on the Institute of Medicine (IOM, now the National Academy of Medicine) 2009 pregnancy weight gain guidelines, the reference most US care providers use, extended with IOM's separate provisional guidance for twin pregnancies.