What is femur length?

Femur length refers to the length of the fetus's thigh bone, which is a relatively important indicator during a woman's pregnancy. The doctor can determine whether the fetus is developing normally by the femur length shown in the B-ultrasound, and make a judgment based on some standards of femur length. It is unscientific to judge the gender of a baby based on the length of the femur. Let’s take a look at this aspect below and hope it will be helpful to you.

What does femur length mean?

Femur length is an indicator used by doctors to observe whether the fetal development is normal when they perform pregnancy check-ups on pregnant women using B-ultrasound or color ultrasound.

Femur length is actually the length of the thigh bone. The femur is the largest long bone in the human body. It and the humerus are both typical long tubular bones in the human body. The humerus is located in the upper arm, also called the upper arm bone. The length of the humerus refers to the length of the upper arm bone. Doctors use femur length and humerus length to predict fetal weight, but fetal humerus length is better than femur length in predicting fetal weight.

Femur length standard

The standard value of femur length is generally calculated from the 13th week of pregnancy, because the early pregnancy (1-12 weeks of pregnancy) is the process from the beginning of implantation of the fertilized egg to the initial development of the fetal reproductive organs, after which the various organs tend to be perfected. Therefore, it is recommended to start checking the femur length from 13 weeks. Next, let’s take a look at the standards for fetal femur length at different gestational weeks.

Note: As the gestational age increases, the femur length value will gradually increase because the fetus's height and weight are gradually increasing. In addition, pregnant mothers do not need to be too nervous about the above data, because the fetus moves more in the mother's belly, and different fetal positions and different doctors' operations will cause errors in the data, and sometimes even large fluctuations. Experts say that after 30 weeks of pregnancy, an error of two weeks is allowed, so when pregnant mothers see that the report results are different from the normal values, they do not need to be too nervous. If there is indeed a problem after the reexamination, consult a doctor and seek a solution.

Biparietal diameter femoral length determines gender

The growth of the femur is used to observe whether the fetal development is normal. People also use the femur length and biparietal diameter to determine the gender of the fetus. Let's learn about it together. Judgment method: If the value of the fetal biparietal diameter minus the femur length is greater than 2, the possibility of having a boy is relatively high. If it is less than 2, the probability of having a girl is high. Moreover, the larger the difference, the more accurate it is, and the more accurate it becomes in the later stages.

Experts told us that this method is actually unscientific. The biparietal diameter and femur length are used by doctors to estimate the weight and size of the fetus, and are an indicator for predicting fetal weight. In addition, the measured biparietal diameter and femur length data will also be different due to different fetal positions. Therefore, it is inaccurate to determine the gender of the baby based on the biparietal diameter and femur length. If you want to determine the sex of the fetus, you can choose to have an ultrasound examination.