Overweight pregnancy weight gain at week 20
Here’s the recommended pregnancy weight gain so far for a overweight pre-pregnancy BMI at week 20.
Different category or week? Use the full pregnancy weight gain calculator above.
About the pregnancy weight gain calculator
This calculator is based on the total pregnancy weight gain ranges published by the Institute of Medicine (IOM, now part of the National Academy of Medicine), which set recommended gain ranges according to pre-pregnancy BMI category: 28-40 lb for underweight, 25-35 lb for normal weight, 15-25 lb for overweight, and 11-20 lb for obese. These ranges reflect research on outcomes for both parent and baby, and they're the guideline most U.S. obstetric providers reference when discussing healthy weight gain during pregnancy.
Rather than just showing the total range, this tool also estimates how much of that total you'd typically have gained by a given week, since weight gain isn't meant to happen evenly across all 40 weeks. During the first trimester (weeks 1-13), total recommended gain is a flat 3 lb regardless of starting BMI category, scaled linearly across those early weeks — reflecting that most people gain very little in the first trimester even though the baby is growing.
From week 14 onward, the prorated estimate assumes a steady linear rate of gain from that 3 lb mark at week 13 up to the midpoint of your category's total range by week 40. For example, in the normal weight category (25-35 lb range, midpoint 30 lb), the model gains at (30 − 3) ÷ (40 − 13) ≈ 1 lb per week from week 14 through week 40. This linear approach is a simplification — real second- and third-trimester gain often follows a slightly different curve — but it gives a reasonable checkpoint for whether you're broadly on track.
This calculator is a general educational guideline only, not personalized medical advice. It does not account for twins or higher-order multiples, which have their own higher recommended gain ranges, nor does it account for individual medical history, pre-existing conditions, or how your pregnancy is actually progressing. Always follow the specific guidance your OB, midwife, or maternal-fetal medicine provider gives you, since they're accounting for factors this general calculator can't see.
Use this tool as a conversation starter or a rough sanity check between prenatal visits, not as a target to hit exactly. Weight gain naturally varies week to week — a single low or high week rarely means anything on its own, and your care provider is tracking your overall trend across the full pregnancy, not any one data point.
Pregnancy weight gain calculator questions
How IOM recommended weight gain ranges are calculated.
How much weight should I gain during pregnancy?
It depends on your pre-pregnancy BMI category. The IOM guidelines recommend 28-40 lb total for underweight, 25-35 lb for normal weight, 15-25 lb for overweight, and 11-20 lb for obese pre-pregnancy BMI.
How much weight should I have gained by a specific week of pregnancy?
This calculator prorates your category's total range across the pregnancy: a flat 3 lb by the end of the first trimester (week 13) regardless of category, then a linear increase from week 14 to week 40 up to the midpoint of your total recommended range.
Why is first trimester weight gain recommended to be so low?
Most people gain very little in the first trimester — often just 1-5 lb total — even though the baby is developing rapidly, since the baby itself is still very small. This calculator uses a flat 3 lb estimate for the first 13 weeks across all BMI categories.
Does this pregnancy weight gain calculator work for twins?
No. This calculator uses the IOM's singleton pregnancy guidelines. Twin and higher-order multiple pregnancies have their own, higher recommended weight gain ranges — ask your OB or maternal-fetal medicine provider for guidance specific to a multiples pregnancy.
What BMI category should I use if I don't know my pre-pregnancy BMI?
Use your BMI from just before you became pregnant, if you know it: under 18.5 is underweight, 18.5-24.9 is normal weight, 25-29.9 is overweight, and 30 or above is obese. Ask your provider if you're unsure which category applies to you.
Is this pregnancy weight gain calculator a substitute for medical advice?
No — it's a general educational guideline based on IOM recommendations, not personalized medical advice. Always follow the specific guidance from your OB or midwife, who can account for your individual health history and how your pregnancy is progressing.