There is no absolute conclusion on whether a man taking entecavir will cause fetal malformations, and the likelihood of fetal malformations caused by the drug in general is relatively small. Entecavir is an antiviral drug that inhibits the replication of the hepatitis B virus. There is no clear evidence that entecavir has any effect on sperm genetics or fetal development. A woman needs to have vigorous sperm to be able to conceive normally. The drug taken by the male partner has an effect on the sperm, which may lead to a decrease in sperm motility or a decrease in the number of sperm, preventing the formation of a fertilized egg. If a pregnancy is successful, it is usually possible to obtain a normal embryo. This product is contraindicated in people who are allergic to entecavir and any of the entecavir excipients, and should be used with caution in pregnant and lactating women, and in patients with renal insufficiency. Adverse reactions such as visible diarrhea, dyspepsia, nausea, vomiting, malaise, headache, dizziness, drowsiness and insomnia may occur after the use of the drug. It is important to have regular and proper pregnancy checkups after confirming pregnancy to be able to detect any fetal malformations.