Can a gırl get pregnant by having sex immediately after menstruation?
First, let's start out with the facts:
- A woman releases an egg 14 days before the beginning of her next period. The difficulty comes in predicting when a woman's next period will start. Most women have a 28 day cycle between periods (measured from start to start) but it can be as short as 14 days or as long as 36 days. For some women, especially teenagers, it is not unusual to skip a period once in a while.
- A man's sperm can survive up to six days in a woman after sex. The numbers die off with each passing day, but even out to the sixth day there can be sufficient quantities of sperm to cause conception.
- The female egg must be fertilized on the day it is released for conception to take place.
This chart attempts to illustrate the problem by showing four sample periods of 14, 21 28, and 35 days. In reality the number of days can be anywhere between 14 and 36. Sex in any of the red or green area means there will be sperm present that can cause a pregnancy on the day that the egg is released (the green area).
Since you don't know in advance how long a girl's period will be, there is no day that can guarantee that a girl may not get pregnant. Even sex during or before a girl's period could result in a pregnancy if she has a short cycle that month. Since a girl's period lasts about five days, sex right after the period ends can result in pregnancy if the girl's cycle that month is between 19 and 25 days.
Every act of sex carries the possibility of pregnancy. Even contraceptives, such as condoms or the pill only lower the odds; they cannot guarantee that a pregnancy will never happen. Thus, this is just one reason sex belongs only in marriage. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). Guys tend to focus on the excitement of sex and forget that it can lead them to becoming fathers, even if they are not ready for that responsibility. Inside marriage, it isn't that big of a deal because you expect children to eventually come. But outside of marriage it not only alters the boy and girl's lives, it also impacts the life of child conceived. See: Waiting for the Proper Time