Pregnancy Weight Gain Guide

IOM-recommended weight gain ranges by pre-pregnancy BMI, with trimester breakdown.

Your Pre-Pregnancy Height

Your Pre-Pregnancy Weight (lbs) Carrying:

IOM Weight Gain Recommendations

Pre-Pregnancy BMI	Category	Total Gain (Single)	Total Gain (Twins)	2nd/3rd Trimester Rate
< 18.5	Underweight	28–40 lbs	—	~1 lb/week
18.5–24.9	Normal weight	25–35 lbs	37–54 lbs	~1 lb/week
25.0–29.9	Overweight	15–25 lbs	31–50 lbs	~0.6 lb/week
≥ 30.0	Obese	11–20 lbs	25–42 lbs	~0.5 lb/week

IOM = Institute of Medicine (now National Academy of Medicine). These are guidelines, not requirements. Discuss your personal target with your OB.

Where Does the Weight Go?

At 40 weeks, the average weight breakdown for a 30-lb total gain:

Component	Weight
Baby	7.5 lbs
Placenta	1.5 lbs
Amniotic fluid	2 lbs
Uterus (growth)	2 lbs
Breast tissue	2 lbs
Increased blood volume	4 lbs
Body fluid (swelling)	4 lbs
Maternal fat stores	7 lbs

💡 First trimester weight gain is typically only 1–4 lbs total. The majority of weight gain (roughly 1 lb per week) happens in the second and third trimesters.