Pregnancy Weight Gain — overweight, week 20
The IOM-recommended weight gain range for overweight, week 20. Adjust any field below to try your own height, weight, and week.
Recommended Total Gain
15–25 lbs
Pre-Pregnancy BMI
27 (overweight)
2nd/3rd Trimester Rate
~0.6 lb/week
Expected by Week 20
5.4–8 lbs
Result
At a pre-pregnancy BMI of 27 (overweight), the IOM recommends a total gain of 15-25 lbs over the full pregnancy. By week 20, expected cumulative gain is roughly 5.4-8 lbs.
Expected cumulative gain range across pregnancy
What is a Pregnancy Weight Gain Calculator?
How much weight is healthy to gain during pregnancy depends heavily on the weight you started at, measured by pre-pregnancy BMI. The Institute of Medicine (IOM) publishes total-gain guidelines by BMI category — underweight, normal weight, overweight, and obese — because gaining the same amount regardless of starting weight isn't appropriate for every body.
This calculator converts your pre-pregnancy height and weight into a BMI category, looks up the matching IOM recommended total gain range, and estimates where you should be at any given week so far — plus how your actual gain (if you enter it) compares to that expected pace.
Expected Gain by Week
A snapshot of the recommended cumulative gain range at several points through pregnancy, for a overweight pre-pregnancy BMI.
| Week | Expected Cumulative Gain (lbs) |
|---|---|
| 0 | 0–0 |
| 2 | 0.2–0.4 |
| 4 | 0.5–0.8 |
| 6 | 0.7–1.2 |
| 8 | 0.9–1.5 |
| 10 | 1.2–1.9 |
| 12 | 1.4–2.3 |
| 14 | 2.5–2.9 |
| 16 | 3.4–4.6 |
| 18 | 4.4–6.3 |
| 20 | 5.4–8 |
| 22 | 6.3–9.7 |
| 24 | 7.3–11.4 |
| 26 | 8.3–13.1 |
| 28 | 9.2–14.8 |
| 30 | 10.2–16.5 |
| 32 | 11.1–18.2 |
| 34 | 12.1–19.9 |
| 36 | 13.1–21.6 |
| 38 | 14–23.3 |
| 40 | 15–25 |
IOM Recommended Total Weight Gain
| Pre-Pregnancy BMI Category | Singleton Pregnancy | Twin Pregnancy |
|---|---|---|
| Underweight (BMI < 18.5) | 28-40 lbs | Not officially established |
| Normal weight (18.5-24.9) | 25-35 lbs | 37-54 lbs |
| Overweight (25.0-29.9) | 15-25 lbs | 31-50 lbs |
| Obese (30.0+) | 11-20 lbs | 25-42 lbs |
The IOM has not published an official twin-pregnancy range for underweight BMI; this calculator uses a conservative extrapolation above the normal-weight twin range and flags it as such.
Why Recommendations Vary by Starting BMI
A pregnancy's healthy weight gain isn't one-size-fits-all because it accounts for the combined weight of the baby, placenta, amniotic fluid, increased blood volume, and maternal fat stores — but someone starting underweight generally needs to gain more to support fetal growth adequately, while someone starting obese needs less additional gain because they already carry larger energy reserves. Gaining too little is linked to low birth weight; gaining too much is linked to a harder delivery and higher risk of retaining weight postpartum.
Why Gain Isn't Linear Across Pregnancy
Most of the recommended gain happens in the second and third trimesters, not the first. General guidance suggests only 1-4 pounds total gain during the first trimester (weeks 1-13), since the fetus is still very small — most nausea-related appetite changes also occur during this window. From the second trimester onward, growth accelerates, and the recommended pace becomes roughly a pound a week for someone at a normal starting BMI (less for overweight/obese, slightly more for underweight).
Twin Pregnancies Need More
Carrying twins means supporting two placentas, more amniotic fluid, and two growing babies, so IOM guidelines recommend meaningfully higher total gain than a singleton pregnancy at the same starting BMI — for example, 37-54 lbs for a normal-weight BMI carrying twins, versus 25-35 lbs for a normal-weight singleton pregnancy.
Example — Your Current Inputs
At a pre-pregnancy BMI of 27 (overweight), the IOM recommends a total gain of 15-25 lbs over the full pregnancy. By week 20, expected cumulative gain is roughly 5.4-8 lbs.
Additional Example — A Normal-Weight Singleton Pregnancy
A woman with a pre-pregnancy BMI of 22 (normal weight) is recommended a total gain of 25-35 lbs over the full pregnancy. By week 30, roughly three-quarters of the way through, she would expect to have gained somewhere around 20-27 lbs so far, with the remaining gain happening gradually over the last ten weeks.
About These Parameters
- Pre-Pregnancy Height and Weight
- Your height and weight before becoming pregnant — together these determine your pre-pregnancy BMI, which is the single biggest factor in how much weight gain is recommended.
- Current Week of Pregnancy
- How far along you are, from 1 to 42 weeks, used to estimate how much of your total recommended gain should have already happened by now.
- Current Weight (Optional)
- Your weight right now. If provided, the calculator compares your actual gain so far against the expected range for your current week, so you can see if you're tracking below, within, or above the recommendation.
- Twins
- Check this if carrying twins — the recommended total gain range increases substantially compared to a singleton pregnancy at the same starting BMI.
Frequently Asked Questions
What if I'm gaining faster or slower than the recommended range?
A single week outside the range usually isn't cause for alarm — gain naturally varies week to week — but a sustained pattern of gaining much faster or slower than recommended is worth discussing with your OB-GYN or midwife, since they can factor in details this calculator can't, like multiple pregnancies, medical history, or fetal growth measurements.
Why is the recommended range lower for someone who was overweight before pregnancy?
Because pre-pregnancy body fat stores already provide some of the extra energy reserves pregnancy calls for, so less additional gain is needed to support a healthy pregnancy — the goal is a healthy outcome for both parent and baby, not a fixed number that applies to everyone.
Does this calculator account for medical conditions like gestational diabetes?
No — this tool applies general IOM population guidelines only. Specific medical conditions can change the appropriate weight gain target, so always follow guidance from your own prenatal care provider over a general calculator.
Is it normal to lose weight in the first trimester?
Yes — nausea and appetite changes are common in the first trimester, and a small weight loss or plateau in the first 13 weeks is generally not a concern as long as gain picks up in the second trimester as expected.