What is the biparietal diameter at 18 weeks? Is it a boy?

During the pregnancy process, many parents are very concerned about the gender of the child. Some of them do so because they prefer boys to girls and want to know whether the child is a boy, while others are purely curious and do not have any particular gender discrimination mentality. During pregnancy, it is very important to check the biparietal diameter, and some people are concerned about its relationship with boys. So, what is the biparietal diameter at 18 weeks for a boy? Let’s take a look below.

This is how most people determine the sex of the fetus:

If the biparietal diameter is subtracted from the femur length and the resulting data is greater than 21mm, it is a son, otherwise it is a daughter. The reason is: boys have big heads and short legs, while girls have long legs and small heads.

The fetal biparietal diameter refers to the length of the widest part between the left and right sides of the fetal head, also known as the "great transverse diameter of the head." Also known as BPD, doctors often use it to observe fetal development, determine whether there is cephalopelvic disproportion, and ensure a smooth delivery.

Specific analysis:

1. It should reach 9.3 cm or above at full term. According to general rules, after 5 months of pregnancy, the BPD is basically consistent with the month of pregnancy, that is, at 28 weeks of pregnancy (7 months) the BPD is about 7.0 cm, at 32 weeks of pregnancy (8 months) it is about 8.0 cm, and so on.

2. After 8 months of pregnancy, an average weekly growth of about 0.2 cm is normal. When the due date cannot be determined by CRL (crown-rump length) in the early stages of pregnancy, BPD is often used to predict it; after the second trimester, this data is often also needed to be measured when estimating the fetal weight.

Kind tips:

1. It is inaccurate to use the biparietal diameter to determine whether the fetus is male or female. The determination of the baby's gender is related to the biparietal diameter length, but the gender of the fetus cannot be determined solely based on the biparietal diameter femur length.

2. Biparietal diameter and femur length are only indicators of fetal development and have nothing to do with the gender of the fetus. Therefore, pregnant mothers can only treat them as pastime and entertainment and should not take them seriously.

How to tell the gender of a man from his biparietal diameter

It must be stated again that it is unscientific to use the biparietal diameter to determine whether the fetus is male or female. The biparietal diameter cannot determine the sex of the fetus, but the biparietal diameter can be used to calculate the weight of the fetus.

Specific analysis:

1. Biparietal diameter, also known as BPD, is the biparietal diameter of the fetal head. It refers to the length of the widest part between the left and right sides of the fetal head, also known as the "greater transverse diameter of the head." Doctors often use it to observe the child's development and determine whether there is cephalopelvic disproportion and a smooth delivery.

2. It should reach 9.3 cm or above at full term. According to general rules, after 5 months of pregnancy, the BPD is basically consistent with the month of pregnancy, that is, at 28 weeks of pregnancy (7 months) the BPD is about 7.0 cm, at 32 weeks of pregnancy (8 months) it is about 8.0 cm, and so on.

3. After 8 months of pregnancy, an average weekly growth of about 0.2 cm is normal. When the due date cannot be determined by CRL in the early stage, BPD is often used to predict it; after the middle stage, this data is often also needed to be measured when estimating the fetal weight.