Your result shows how your current pregnancy weight gain compares to the Institute of Medicine (IOM) 2009 guidelines for your pre-pregnancy BMI category. If your gain is within the recommended range for your gestational age, you are on track. If you are gaining faster than recommended, you may have increased risk of gestational diabetes, preeclampsia, macrosomia, and difficulty losing weight postpartum. If you are gaining less than recommended, there may be increased risk of preterm delivery and low birth weight.

Weight gain is not linear throughout pregnancy. Most women gain very little in the first trimester (0.5-2 kg total), with the majority of gain occurring in the second and third trimesters at a relatively steady rate. A single measurement that falls slightly outside the range is not necessarily concerning — the overall trajectory over multiple visits matters more than any one data point.

Use this calculator at each prenatal visit to track weight gain trends against IOM guidelines. It is especially useful for women with pre-existing overweight or obesity, those with a history of gestational diabetes, or anyone whose provider has flagged weight gain as a concern. It can also be helpful for women who are anxious about pregnancy weight changes and want an evidence-based reference.

This tool is designed for singleton pregnancies. Women carrying twins or higher-order multiples have different recommended weight gain ranges and should discuss targets with their obstetric provider directly.

The IOM guidelines are population-level recommendations and do not account for individual variation in body composition, ethnicity, or medical conditions. Some studies suggest that the IOM ranges may not be optimal for all racial and ethnic groups, and country-specific guidelines may differ.

This calculator does not distinguish between types of weight gain (fluid retention, fetal growth, fat deposition, muscle changes). Sudden, rapid weight gain may indicate preeclampsia or fluid retention rather than caloric excess and warrants clinical evaluation. Additionally, the calculator cannot detect intrauterine growth restriction or other pregnancy complications — regular prenatal ultrasounds and clinical assessments remain essential.