A normal pregnancy has about 40 weeks, 280 days, or roughly 10 months of gestation, and 13 weeks of pregnancy indicates 3 months plus 1 week of pregnancy. The clinical calculation of pregnancy is different from the solar or lunar calendar months in daily life, as pregnancy is calculated according to 4 weeks as 1 month. The 13 weeks of pregnancy is the middle stage of pregnancy, which has already passed the dangerous period of the first 3 months, and the fetus is basically developed and formed, and the fetal head, bones and other structures can be seen by ultrasound examination, during which the fetus can be initially determined whether it has malformations. The 13th week of pregnancy is safer than the first 3 months, but still we should not take it lightly, make sure to check the fetal development regularly, quit smoking and alcohol, do not expose to radiation and toxic substances, strengthen the nutrition, eat more iron-rich food, such as animal offal, and can be properly active to help avoid complications such as high blood pressure during pregnancy.