About & Editorial Policy
Who we are
genderpredictor.app is a small independent project made by Vadim Semenko, the developer of the BabyPeek iOS app. The site explains the popular ways parents try to guess a baby's sex before the anatomy scan: the Chinese gender calendar, nub theory, Ramzi theory, skull theory, ultrasound signs, and old wives' tales.
We are not doctors, sonographers, or a medical organization. Nothing here is medical advice, and no guide on this site is reviewed by a clinician. We say so plainly rather than put a doctor's name on a page that no doctor has checked.
How we research
- Primary sources first. Accuracy numbers come from the original studies, most of them indexed in PubMed, and not from other blogs. Every guide lists its sources at the bottom with links.
- We separate evidence from folklore. Nub theory has peer-reviewed studies behind it. The Chinese calendar was tested on 2.8 million births and did no better than a coin toss. Ramzi and skull theory have no controlled evidence supporting them. Each guide says which group a method belongs to.
- We report the limits. Where a study covers a narrow situation, such as clinic-quality scans at a specific week measured by specialists, we say so instead of repeating the headline number.
- No invented numbers. If we could not find a source for a claim, we leave the claim out.
How we write
Guides are written by the BabyPeek editorial team, which is currently the developer, with AI writing tools used for drafting and translation. Every figure and citation is checked by hand against the source before publishing. The date at the top of each guide shows when it was last updated.
Our relationship with the BabyPeek app
This site is a free companion to the BabyPeek app, and guides link to it. The app is a paid product for entertainment. We describe what it does and what it cannot do. It does not replace your doctor's anatomy scan at 18–20 weeks or a prenatal blood test.
Corrections
If you find an error or a study we missed, tell us through the BabyPeek App Store page or at [email protected]. We fix confirmed errors and update the date on the page.
Medical disclaimer
For entertainment only. Only a medical test, such as NIPT or an anatomy scan read by a professional, can reliably tell a baby's sex. Please talk to your doctor or midwife about anything related to your pregnancy.