How reliable is the estimation if after an ultrasound at 18 weeks they could not tell sex of baby but offered a guess?

The reliability of an ultrasound to determine the sex of a baby at 18 weeks depends on several factors, including the experience of the sonographer, the quality of the ultrasound equipment, and the position of the baby. In general, an experienced sonographer using high-quality equipment should be able to determine the sex of the baby with a high degree of accuracy by 18 weeks. However, there are some cases where the baby's position may make it difficult to obtain a clear view of the genitalia, which could lead to an incorrect guess or an uncertain result.

According to the American College of Obstetricians and Gynecologists (ACOG), the accuracy rate for ultrasound in determining fetal sex is approximately 90% by 18 weeks. However, this accuracy rate can vary depending on the individual sonographer and the specific ultrasound equipment used. It is important to note that an ultrasound guess of the baby's sex is not a definitive diagnosis, and it is possible for the sonographer to be mistaken. If the sonographer is uncertain about the sex of the baby, they may recommend a follow-up ultrasound at a later stage of pregnancy to confirm the results.

Overall, while an ultrasound at 18 weeks can provide a good indication of the baby's sex, it is not always 100% reliable and should not be considered a definitive determination.