HEL How many months after fertilisation is the birth of the baby?

The unborn baby spends around 38 weeks in the uterus, but the average length of pregnancy, or gestation, is counted at 40 weeks. Pregnancy is counted from the first day of the woman's last period, not the date of conception which generally occurs two weeks later.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.