Learn about how conception works.

It all begins with an egg …

The average menstrual cycle lasts 28 days; the first day of the cycle is the first day of menstruation.

During the first 14 days of the average cycle, an egg matures in a woman’s ovaries. A hormone called follicle stimulating hormone (FSH), stimulates this process. The coat around the egg produces estrogen. This hormone makes the lining of the uterus grow to form a nutritious and secure bedding for the egg to settle into after fertilization.

Around day 14 of the average cycle, the mature egg is ready to be released. Another hormone, called luteinizing hormone (LH), gives the impulse for the egg to emerge from the ovary and be taken up by the fallopian tube. This important event is called ovulation. This is also the most fertile time of the month for the woman to get pregnant.

The egg must be fertilized by sperm within six to 12 hours of ovulation. At this time the egg is still high in the fallopian tube. Fertilization happens when a sperm enters the egg and the embryo starts to form. Two cells divide and become four, the four cells divide and become eight, and so on. By the time the cluster of cells reaches the uterus and settles down into the lining of the uterus, it has become an embryo. It usually takes around seven days for the egg (fertilized or not) to travel though the fallopian tube to the uterus.

As the egg is travelling down the fallopian tube, the rise of estrogen and progesterone in the blood stream of the woman, along with the pregnancy hormone HCG from cells surrounding the embryo, signals pregnancy. From now on, the female body concentrates on the growth of the embryo and stops the cycle until a few weeks after the baby is born. This is why women cannot conceive again while they are pregnant. A woman can only have one pregnancy at a time, but this does not exclude the possibility of having more than one embryo or fetus at a time, e.g. twins.

Am I pregnant?

Pregnancy tests measure the level of pregnancy hormone (HCG) in your blood or urine. HCG can be detected in your blood as early as 6-8 days after conception. A urine pregnancy test can’t detect HCG in the urine until the day you expect your period, at the earliest. Most urine pregnancy tests are sensitive enough to detect a pregnancy by the first day of a missed period. You should do a urine pregnancy test at the time when you would expect your period. If you do it too soon, the result may not be accurate. Some test kits may tell you that if the test is negative, you should repeat it in 1 to 2 weeks. Make sure you follow the instructions on the kit carefully and that it hasn’t passed its expiry date.

If the test was positive, you are likely pregnant. A home urine pregnancy test tells you whether or not the pregnancy hormone HCG is in your urine. A positive result is quite accurate because the test will not register the presence of HCG unless it is actually there. False positives (when the test tells you that you are pregnant and you are not) are very rare.

A home pregnancy test only measures the presence or absence of pregnancy hormone (HCG). It can’t tell you whether a pregnancy is healthy or whether you have had a miscarriage. If a home pregnancy test is positive, contact your healthcare provider or a health clinic to schedule a visit. In the meantime, you should take care to eat well and avoid alcohol, drugs, and tobacco. You should also take a prenatal vitamin that contains folic acid.


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