• 28th October 2019

Determining gender at 15 weeks + 3 days

scanning studio

Determining gender at 15 weeks + 3 days

Determining gender at 15 weeks + 3 days 1024 386 Original Window to the Womb

Our baby’s gender is determined at the moment of conception. If Dad’s sperm contributes a Y chromosome, it creates a boy, or the X chromosome, which creates a girl. Boys’ and girls’ genitals look the same with no outward sign of gender until about nine to 10 weeks. At this point the genital tubercle begins to develop into a penis or clitoris. However, it’s not until 15 weeks that you can clearly begin to see the difference in baby’s genitalia.

A mother’s weight can also affects our ability to predict gender. The more body tissue the ultrasound waves travel through, the fuzzier and shadowed the images could be. It’s really important to have a full bladder for a early 15 week + baby scan, it makes a huge difference to the image quality and our ability to gender baby correctly.

The Baby’s position seen during a Baby Scan

Finally baby’s position can sometimes make it impossible to see.  If baby has their bottom push down into the lower pelvis or is simply sitting up with their legs tucked under their bottom we can’t get a good view.  To determine baby’s gender we need to look up and under baby’s bottom, we look for 3 white lines, which is the labia of a baby girl, or obvious sticky out bits, the penis of a baby boy.

Even at 15 weeks+3 days there are factors which can cause us to mistake the gender.

Little girls can have swollen labia which can look like boy bits. Little boys can have undescended testicals making them look like girls.
When sexing your baby we take care to see and reproduce babies gender from as many angles as possible and only tell you when we have seen the positive sign for each sex. If we are unable to get a positive result we would ask you to return for a rescan. As we’re sure you understand that Ultrasound is never 100%, we rely on our Sonographers skill and expertise on every scan.


At the Original Window to the Womb we specialize only on gender and 3D ultrasound all our Sonographers have worked with us for over 5yrs some have been with us since we opened in 2003.

Free Rescan Guarantee

All our gender scans come with a free rescan guarantee if we can’t determine gender on the day – we pride ourselves in a 99.9% accuracy scanning over 60,000 babies over the last 16 years. Our 3D Scan, 4D Scan and HD live scans also all carry a free rescan if we can’t obtain good images.

Our scans all include images so no hidden upells.

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