# Nub theory for baby sex prediction unreliable, studies show 2026-08-08T13:37:38+00:00 | World & Diplomacy | Indian Opinion Desk Corroboration: 1 independent outlet A viral trend called "nub theory" claims parents can predict a baby's sex from a 12-week ultrasound by measuring the angle of the genital tubercle. But research shows the method is highly unreliable early in pregnancy, one 2012 study found accuracy as low as 30% before 11 weeks, barely better than a coin flip. Accuracy improves to about 90% by 12-14 weeks, but still lags behind medical tests like cell-free DNA blood tests (NIPT) or the standard anatomy scan at 18-22 weeks, which are far more dependable for determining fetal sex. ## Coverage - english.mathrubhumi.com Tags: baby sex prediction, medical accuracy, NIPT, nub theory, pregnancy, ultrasound Canonical: https://indianopinion.org/nub-theory-for-baby-sex-prediction-unreliable-studies-show/ License: Summary and commentary (c) Indian Opinion, reusable with attribution. Facts belong to the linked sources. Cite: https://indianopinion.org/nub-theory-for-baby-sex-prediction-unreliable-studies-show/#story-in-brief Review state: restored archive article, accurate at time of publication, not offered to search indexes.