The Sperm's Long Journey. A man may ejaculate 40 million to150 million sperm, which start swimming upstream toward the fallopian tubes on their mission to fertilize an egg. Fast-swimming sperm can reach the egg in a half an hour, while others may take days. The sperm can live up to 48-72 hours. Only a few hundred will even come close to the egg, because of the many natural barriers that exist in a woman's body.
9.4 Giving birth. Normal delivery. Children that are born between the 36th and 39th week (38 and 41 weeks after the LMP) are considered as being normal deliveries. Statistically, only 2/3 of all children are born within the 3 weeks around the calculated date of birth and around 80 % within a month around the predicted date of birth.
If you do know the date of your last period, try the following calculation, called Naegeleâs Rule. Babies have a gestational period of about 280 days, so count back 3 months from the first day of your last period and add 7 more days. Your approximate due date is that day within the next year.Take note of the word âapproximate:â Your baby will grow and mature on his own schedule. The only thing youâll know for sure is that you should give birth within two weeks before or after that day.emember: Your due date is an estimate of when you will give birth, not a guarantee. If you are âover due,â just count it as more time to establish a bond with your baby, to prepare mentally for motherhood, to discuss your partnerâs role during the birth and to ready your home for your babyâs arrival.