Fertility problems are for 14% caused by problems with the Fallopian tubes, 3% is caused by problems with the cervical mucus and 6% sexual problems. On average 2-3 times coitus (sexual intercourse) a week should be enough to establish a pregnancy. After ejaculation the spermcells first are exposed to the low pH within the vagina. The spermcells are sensitive for this pH and seek refuge in the mucus produced by the cervix.

This mucus is composed in such a way that spermcells can only penetrate this mucus during the fertile period of the monthly cycle. This change is accomplished by the hormonal change that occurs around ovulation.

The mucus functions as a resevoir for spermcells from which they continuously progress further into the reproductive tract. Good spermcells are under favourable conditions capable to survive for 3-4 days. See this picture.

Under normal conditions ovulation occurs halfway through the menstrual cycle. The 3-4 days in advcance of the event are the most fertile periode. After ovulation the oocyte will decend in the direction of the uterus.

The length of the fertile window (fertility window)

The "fertility window" is every month approximately open for 4 days. Click here for a schematic overview of the uterus, the relation between

The cervical mucus and very poor sperm
The cervical mucus and poor sperm
The cervical mucus and hormal sperm

Click here for the concept "fertility window".

During the fertile period once or twice sexual intercourse are normally enough to establish a pregnancy. After the spermcells have passed the cervix they continue their journey through the uterine cavity and the Fallopian tubes (which should be open) towards the ovaries where at any moment the oocyte will ovulate.

The figure below shows a cross-section of the uterus, Fallopian tubes and ovaries.