Under normal circumstances, human embryonic nerve tube starts to close on the 21st day after conception (the regular menstrual cycle is 28 days, equivalent to the 35th day after the last menstruation), and will be closed on the 28th day (equivalent to the 42nd day after the last menstrual period)Complete closed.
During this period, if the folic acid level in the mother’s body is insufficient, the fetal nerve tube is closed, which may cause obstacles, causing nerve tube defects, such as no brain and spine bifida.Therefore, supplementation of folic acid should start before pregnancy.If folic acid is supplemented after learning of conception, the best time to prevent neural tube malformation is missed.
For women without high risk factors, starting from 3 months of pregnancy or at least 3 months before pregnancy, 0.4 mg or 0.8 mg folic acid is added daily until 3 months of pregnancy; for women with a history of neural tube defects, they should be pregnant or may be pregnant orStarting at least 1 month before pregnancy, 4mg of folic acid is added daily until 3 months of pregnancy.There are currently no 4mg folic acid type in China, and 5mg folic acid can be added daily.
For the prevention of fetal nerve tube defects, it is enough to supplement folic acid until 3 months of pregnancy.However, since folic acid has other benefits to pregnant women or fetuses, the entire pregnancy period can be supplemented daily or composite vitamins containing folic acid.
HCG, a Chinese name, is human chorionic gonadotropin. It is a kind of glycoprotein hormone secreted by the nourishing cells of fertilized eggs.After the embryo is bed, HCG enters the mother’s blood circulation. At this time, HCG can be detected through blood or urine detection.
In the early stages of pregnancy, the secretion of HCG has increased rapidly, which has the characteristics of "double", which can be doubled every 1.7 to 2.7 days.The secretion of HCG at 8 to 10 weeks of pregnancy reaches its peak, which has decreased after 1 to 2 weeks.
Normally without pregnant women, there are almost no HCG secretion in men. Some diseases such as nourishing cell tumors can secrete HCG, but this situation is rare.Therefore, you can determine whether you are pregnant by detecting blood HCG.
Due to the characteristics of HCG’s "double", in the early pregnancy, you can also dynamically observe the growth of HCG and initially judge the development of early embryos.For example, most of the biochemical pregnancy and ectopic pregnancy, HCG’s growth is not good.
However, the secretion of each person is very different, and the HCG level and embryo development are not an absolute linear relationship.Therefore, the good and bad of the embryo cannot be judged based on the absolute value of HCG.
It should be noted that HCG monitoring is just a monitoring method, which helps to discover an early ectopic and biochemical pregnancy in the early days. It cannot replace the ultrasonic diagnosis. In the end, it is necessary to determine the development of the embryo bed and embryo through the B -ultrasound.
This article was scientifically controlled by Wang Huichun, director of the reproductive center of the Maternal and Child Health Hospital of Haidian District, Beijing.
(Responsible editors: Wu Yiwen, Wang Yanhua)