A study to evaluate accuracy of gestational age, comparing conventional method against duration of intermenstrual interval consideration

Pawanpreet Kaur, Deepak A. Desai, Aartee Taraiya


Background: Most methods of calculating gestational length are based upon 28 day cycle. If a woman has a cycle which is significantly shorter than 28 days and she delivers before her due date calculated by her LMP, this arises an anticipation of a premature baby, but the fetus is mature by all criteria of maturity assessment. Dr. Modi (Text Book of Medical Jurisprudence) stated, ‘duration of pregnancy in homo homosapiens is 10 times the inter-menstrual interval’. Keeping this in mind we undertook this study.

Methods: The study was done for a duration of 1 year. The gestational age of patients was calculated from the routine Naegele’s formula and inter-menstrual interval. The maturity of neonate was assessed by using Ballard’s score. This data was co-related for further evaluation.

Results: Although 39 (19.5%) neonates were expected to be preterm, 24 (12%) actually turned out to be preterm according to Ballard’s score. Rest 15 neonates, premature by Naegele’s formula, should be in “premature” group, turned out to be well developed, by Ballard’s score, almost 37.5% of early delivery group, (significant at P<0.05)

Conclusions: This showed that the baby attained maturity at a lesser gestational age which corresponded to 10 times the inter-menstrual interval.


Intermenstrual interval, Ballard’s score, Preterm

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