ObsCalc India — Free Obstetric Calculator Suite for Doctors
This free obstetric calculator suite covers all common bedside calculations for Indian obstetricians — gestational age, fetal weight, cervical scoring, newborn assessment, GDM screening, VBAC eligibility and PPH risk. All calculators follow FOGSI, ACOG, RCOG and WHO guidelines.
Gestational Age Calculators
GA by LMP: Naegele's Rule — EDD = LMP + 280 days adjusted for cycle length. Shows current GA, trimester and EDD.
GA by Scan: Back-calculates EDD from ultrasound GA. Most accurate in the first trimester using CRL.
GA on Any Given Date: Calculates the exact gestational age on any specified date — for operation notes and discharge summaries.
LMP from EDD: Reverse calculator — enter a known EDD to find the equivalent LMP and approximate conception date.
Fetal Assessment
Expected Fetal Weight (Hadlock): Hadlock 1985 formula — standard in Indian practice. 4-parameter (BPD+HC+AC+FL) preferred, 3-parameter (BPD+AC+FL) used when HC unavailable. Includes ±15% range and approximate SGA/AGA/LGA classification.
Apgar Score: Calculates score from 5 criteria — Appearance, Pulse, Grimace, Activity, Respiration. 7–10 normal. 4–6 requires intervention. 0–3 requires immediate resuscitation.
Obstetric Scoring
Bishop Score: Assesses cervical favourability for induction of labour — dilation, effacement, station, consistency and position. Score ≥9 favourable for direct oxytocin. Score <6 requires ripening.
VBAC Eligibility: 8-point checklist per FOGSI/ACOG — scar type, number of CS, presentation, fetal weight, scar thickness, interval, previous SVD and CS indication.
PPH Risk: 15 weighted risk factors giving Low/Moderate/High/Very High risk with specific management protocols per RCOG/FOGSI.
GDM Screening — DIPSI Protocol
DIPSI recommends 75g oral glucose (non-fasting). Blood glucose ≥140 mg/dL at 2 hours = GDM. FOGSI recommends universal screening at first ANC and 24–28 weeks. High-risk women get an additional screen at 32–34 weeks.
Frequently Asked Questions
How is gestational age calculated from LMP?
Using Naegele's Rule — add 280 days to the LMP assuming 28-day cycles. Adjust by adding or subtracting the difference from 28 days for non-standard cycles.
Which Hadlock formula is used for EFW?
Hadlock 1985 is standard in India. The 4-parameter formula (BPD+HC+AC+FL) is most accurate. Results have ±15% variability and should be combined with clinical findings.
What is a good Bishop score for induction?
Score ≥9 highly favourable — direct oxytocin appropriate. Score 6–8 favourable. Score <6 requires cervical ripening.
What is DIPSI GDM screening?
75g glucose non-fasting test — blood glucose ≥140 mg/dL at 2 hours is diagnostic. Recommended universally for all Indian pregnant women by FOGSI.
What are VBAC criteria in India?
Single low transverse LSCS, cephalic presentation, scar ≥3.5mm, no recurring indication, interval ≥18 months. Requires emergency CS access and continuous CTG.