IOM 2009 recommended weight gain
The Institute of Medicine (now National Academy of Medicine) published evidence-based gestational weight gain targets in 2009 — the global standard adopted by ACOG, WHO, and Pakistan's antenatal care guidelines.
| Pre-pregnancy BMI | Category | Total gain (kg) | Weekly rate (kg) |
|---|---|---|---|
| < 18.5 | Underweight | 12.5–18 | 0.44–0.58 |
| 18.5–24.9 | Normal weight | 11.5–16 | 0.35–0.50 |
| 25–29.9 | Overweight | 7–11.5 | 0.23–0.33 |
| ≥ 30 | Obese | 5–9 | 0.17–0.27 |
Weekly rate applies to the 2nd and 3rd trimesters. Source: IOM 2009, Table 1.
Pregnancy nutrition in Pakistan
Pakistan faces a double burden in pregnancy: undernutrition (anaemia, micronutrient deficiency) affecting women in rural areas and lower socioeconomic groups, and overnutrition (gestational diabetes, excessive gain) rising in urban areas as dietary patterns shift toward processed foods and refined carbohydrates.
Iron-deficiency anaemia affects over 50% of pregnant women in Pakistan (PDHS 2017–18), making adequate iron intake — through foods like red meat, spinach, daal, and iron-fortified flour, alongside vitamin C to aid absorption — especially important alongside weight management.
When to see a doctor about your weight
Weight tracking is a screening tool, not a diagnosis. See your doctor or midwife if: you are consistently below the recommended range (may need nutritional support); you are gaining more than 1 kg per week in the third trimester (may indicate fluid retention or pre-eclampsia); you experience sudden rapid weight gain with swelling of hands and face; or your weight is fluctuating unusually.
Frequently asked questions
How much weight should I gain in pregnancy?
The IOM 2009 guidelines recommend: underweight (BMI < 18.5): 12.5–18 kg; normal weight (18.5–24.9): 11.5–16 kg; overweight (25–29.9): 7–11.5 kg; obese (≥30): 5–9 kg. These ranges are for singleton pregnancies — twin pregnancies require more.
What happens if I gain too little weight?
Insufficient weight gain is linked to preterm birth, low birth weight, and poor fetal growth (intrauterine growth restriction). In Pakistan, where undernutrition in women is common, inadequate gestational gain is a significant contributor to neonatal complications.
What happens if I gain too much weight?
Excessive weight gain increases risks of gestational diabetes, pre-eclampsia, caesarean delivery, macrosomia (large baby), and difficulty losing weight after delivery. It does not mean cutting calories severely — discuss dietary adjustments with a registered dietitian.
Is dieting during pregnancy safe?
Severe calorie restriction during pregnancy is not safe and can harm fetal development. If weight gain is above the recommended range, focus on improving diet quality — reducing refined carbs, fried foods, and sugary drinks — rather than cutting overall calories. Always work with your doctor or dietitian.
How is the weekly gain rate calculated?
The IOM recommends a typical flat gain of 1–2 kg in the first trimester, then a steady weekly rate in the second and third trimesters. For a normal-weight woman this is 0.35–0.50 kg per week. The calculator uses these rates to estimate the expected range at any gestational week.
Do South Asian women need different targets?
The IOM 2009 targets were developed primarily in North American populations. Some evidence suggests South Asian women may have higher gestational diabetes risk at lower BMI values, and some researchers advocate lower upper limits for South Asian women. Discuss with your doctor whether adjusted targets are appropriate for you.
When should I weigh myself during pregnancy?
Weigh yourself once a week at the same time of day, wearing similar clothing, on the same scale. Morning before eating is most consistent. Avoid daily weighing — normal fluid fluctuations of 1–2 kg between days are not meaningful and can cause unnecessary anxiety.
What foods support healthy weight gain in pregnancy?
Focus on nutrient-dense foods: whole grains (atta roti, brown rice, oats), pulses (daal, chickpeas), dairy (dahi, milk), eggs, vegetables, and fruit. Adequate protein, folate, iron, calcium, and DHA are especially important. Limit fried snacks, mithai, and sugary drinks.