How Much Weight Should I Gain During Pregnancy?
IOM guidelines, trimester breakdown, and what every kg is made of - with Singapore-specific advice on Asian BMI cutoffs.
IOM Weight Gain Recommendations by Pre-Pregnancy BMI
The Institute of Medicine (IOM) guidelines are the most widely used reference for pregnancy weight gain. Your recommended range depends on your BMI before pregnancy. Note that Singapore's Ministry of Health uses slightly lower BMI cutoffs for Asians (overweight starts at BMI 23, obese at BMI 27.5) compared to Western standards.
| Pre-Pregnancy BMI | Category | Total Gain (Singleton) | Weekly Gain (T2/T3) |
|---|---|---|---|
| Below 18.5 | Underweight | 12.5 - 18 kg | 0.5 kg/week |
| 18.5 - 22.9 (Asian: 23) | Healthy Weight | 11.5 - 16 kg | 0.4 - 0.5 kg/week |
| 25 - 29.9 (Asian: 23-27.4) | Overweight | 7 - 11.5 kg | 0.28 kg/week |
| 30+ (Asian: 27.5+) | Obese | 5 - 9 kg | 0.22 kg/week |
| Any BMI (twins) | Twin Pregnancy | 17 - 25 kg | Varies by week |
Important for Singapore mums: Asians carry more body fat at lower BMI levels. If you are of Chinese, Malay, or Indian descent, your gynae may advise you to target the lower end of the IOM range, or even slightly below it, to reduce risk of gestational diabetes and large-for-gestational-age babies.
Trimester-by-Trimester Weight Gain Breakdown
Weight gain is not linear across pregnancy. Most of it happens in the second and third trimesters, when your baby is growing rapidly.
| Trimester | Weeks | Expected Gain | What's Happening |
|---|---|---|---|
| First Trimester | 1 - 13 | 0.5 - 2 kg total | Baby is tiny; nausea may cause weight loss early on |
| Second Trimester | 14 - 26 | 5 - 6 kg | Baby grows rapidly; appetite returns; blood volume increases |
| Third Trimester | 27 - 40 | 5 - 6 kg | Baby gains most weight; fluid retention increases near due date |
Some women lose weight in the first trimester due to morning sickness - this is normal. Do not try to make up for lost weight quickly. Gradual gain from T2 onward is healthier for both of you.
Where Does All the Weight Go?
If you gain 13 kg during pregnancy, your baby makes up only about 3.3 kg of that. Here is a breakdown of what the rest is:
Managing Gestational Diabetes Risk Through Weight Gain
Singapore has one of the highest rates of gestational diabetes mellitus (GDM) in the Asia-Pacific region, affecting about 18-20% of pregnancies. This is partly due to genetic susceptibility in Asian women. Gaining weight within recommended ranges is one key way to lower your risk.
Higher GDM Risk If:
- - BMI over 23 before pregnancy
- - Previous GDM in prior pregnancy
- - Family history of type 2 diabetes
- - Previous baby over 4 kg
- - Gaining weight too rapidly in T2
Protective Factors:
- - Staying within IOM gain targets
- - 30 min of gentle exercise daily (walk, swim)
- - Low glycaemic index diet (brown rice, oats)
- - Regular prenatal check-ups (OGTT at week 24-28)
- - Adequate sleep (poor sleep raises insulin resistance)
Your OGTT (oral glucose tolerance test) is done at 24-28 weeks and is a standard part of antenatal care at both polyclinics and private gynaes in Singapore. Do not skip it even if you feel fine.