Pregnancy Weight Gain Calculator

Calculate recommended pregnancy weight gain schedule based on pre-pregnancy BMI

About Pregnancy Weight Gain Calculator

Overview

Our Pregnancy Weight Gain Calculator provides personalized recommendations based on your pre-pregnancy BMI, following the latest Institute of Medicine (IOM) guidelines. Unlike generic advice, this calculator creates a detailed trimester-by-trimester weight gain schedule customized for both single and twin pregnancies, helping you and your healthcare provider monitor healthy progress throughout your pregnancy journey.

Understanding Pregnancy Weight Distribution

Weight gained during pregnancy isn't just your baby. A typical breakdown for a single pregnancy with 12kg (26lb) total gain includes:

Baby: 3-3.5kg (7-8lbs)
Placenta: 0.7kg (1.5lbs)
Amniotic fluid: 0.8kg (2lbs)
Uterus growth: 0.9kg (2lbs)
Increased blood volume: 1.2-1.8kg (3-4lbs)
Increased breast tissue: 0.5-1.5kg (1-3lbs)
Fat stores for breastfeeding: 2.5-3.5kg (5-8lbs)

Weight Gain Guidelines

Single Pregnancy:

Underweight (BMI < 18.5): 12.5-18 kg (28-40 lbs)
Normal weight (BMI 18.5-24.9): 11.5-16 kg (25-35 lbs)
Overweight (BMI 25-29.9): 7-11.5 kg (15-25 lbs)
Obese (BMI ≥ 30): 5-9 kg (11-20 lbs)

Twin Pregnancy:

Underweight: 22.7-28.1 kg (50-62 lbs)
Normal weight: 16.8-24.5 kg (37-54 lbs)
Overweight: 14.1-22.7 kg (31-50 lbs)
Obese: 11.3-19.1 kg (25-42 lbs)

Trimester-Specific Patterns

Weight gain patterns vary throughout pregnancy:

First Trimester (Weeks 1-12): 1-2 kg (2-4 lbs) total
Second Trimester (Weeks 13-26): Steady gain begins
Third Trimester (Weeks 27-40): Continued steady gain

Weekly Gain (After Week 12):

Normal BMI: 0.35-0.50 kg (0.8-1 lb)
Twins: 0.46-0.65 kg (1-1.4 lbs)

Learn More

ACOG Pregnancy Nutrition Guide