What is the femoral length that indicates a male baby?

For many pregnant women, they want to know the gender of their fetus in advance. However, doctors in hospitals will not disclose this information, so pregnant women may choose other methods to make a judgment. Many people try to determine the gender of the fetus by measuring the femur length, which is actually unscientific. The birth of a male fetus is related to many factors, and it is recommended that everyone should not blindly choose unscientific methods to make a judgment.

Situation 1: If the parents are tall and strong, regardless of whether the fetus is male or female, the femur length will usually be greater than 2.1 in the late stages of pregnancy (after 30 weeks). It is not excluded that the femur length may be greater than 2 in the early stages. Parents of this type may not use this method to determine the gender of the fetus. On the contrary, if the parents are not tall or big, starting from the 24th week of pregnancy, the difference between the biparietal diameter and femur length will be greater than 1.7. Subsequently, the difference between the biparietal diameter and femur length will gradually increase during each ultrasound examination. For example, at 24 weeks, the difference is 1.7, at 28 weeks, the difference is 2, and after 30 weeks, the difference is above 2.1. In this case, there is an 80% chance that the fetus carried by this type of mother is a boy.

Situation 2: If the head size of the fetus is larger than expected by at least one week or more during prenatal examination, and the enlargement must be greater than the actual gestational age. For example, the head size at 30 weeks shows a value of 31-32 weeks on the ultrasound. It is not simply defined as a large head when the difference between the biparietal diameter and femur length is greater than 2.

Situation 3: Some fetuses have a head size that corresponds to their gestational age, but their leg length lags behind. In this case, the difference between the biparietal diameter and femur length will be greater than 2 or even more. This situation does not indicate a large head, but rather short legs. Therefore, some mothers may say that this method is inaccurate.

Range of Femur Data: During the 18th week of pregnancy, the femur length data of the fetus is relatively small, and there is a normal range for this data. Parents should be aware of the normal femur length data for their fetus at 18 weeks, which is 2.71 ± 0.46 cm. The difference between the femur length and biparietal diameter is approximately two centimeters. The femur length of the fetus during the 18th week of pregnancy should be 2.71 ± 0.46 cm on ultrasound examination. If the value is below this range, pregnant women should consult a higher-level hospital for further examination to rule out the possibility of limb shortening.

During pregnancy, pregnant women need to undergo regular check-ups as scheduled. They should not skip any examination during pregnancy for the sake of convenience. They should be responsible for the health of their fetus and their own physical well-being.