VitalMetricHub
Educational only — not medical advice. See full disclaimer. Disclaimer

Medical disclaimer

This tool is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult your doctor or qualified healthcare professional before making any health-related decisions. Results are estimates only.

Last medically reviewed: March 2026

Content last updated: March 30, 2026

Pregnancy dating & prenatal care — education

Due-date calculators estimate delivery timing from LMP or conception—they do not replace ultrasound dating or prenatal visits. Weight gain, blood pressure, glucose screening, and fetal growth are managed by your obstetric team.

Reference snapshot

IOM total gestational weight gain (singleton, 2009)

Example — BMI 18.5–24.9: 11.5–16 kg total (25–35 lb). Other pre-pregnancy BMI classes use different ranges on our due-date calculator materials.

Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: National Academies Press; 2009. Ranges are for singleton pregnancies; individual care may differ.

Why dating matters

Accurate dating affects decisions about testing timing, growth interpretation, and induction discussions. Early ultrasound is the standard when LMP is uncertain or cycles are irregular.

Lifestyle foundations in pregnancy

  • Prenatal vitamins with folic acid as directed; avoid alcohol unless your clinician advises otherwise in exceptional cases.
  • Food safety: avoid unpasteurized products and high-mercury fish per public-health guidance.
  • Stay active with clinician-approved exercise; sleep and stress care matter.

Red flags — seek care urgently

Severe headache, vision changes, right-upper-quadrant pain, heavy bleeding, decreased fetal movement, or signs of preterm labor require immediate evaluation—not a calculator.

Sources, formulas & further reading

Based on: Naegele’s rule (LMP + 280 days) and conception + 266 days (educational dating only).

For additional clinical context, see independent references from the publishers below (WHO, CDC, PubMed, Medscape, ACE, ACOG, NIH, NCBI, USDA — as applicable).

Additional references