The length of time that it takes for fertility to return will differ for each woman. It is possible, although rare, for a woman to fall pregnant while on the Pill. There is no evidence that this causes problems for the baby. Women are encouraged to discuss their health needs with a health practitioner.
If you have concerns about your health, you should seek advice from your health care provider or if you require urgent care you should go to the nearest Emergency Dept.
Ovulation and conception Single and lesbian women Optimising conception Section menu. A step-by-step guide to ovulation Every month the pituitary gland, which is in your brain, releases a hormone. This hormone tells the ovaries to produce a number of fluid-filled cysts called follicles. As the follicles grow they secrete the hormone oestrogen. Oestrogen works to thicken the wall of your uterus in preparation for pregnancy. On day seven of your cycle, the follicles stop growing except for one.
This follicle continues to grow and to nourish a maturing egg oocyte within. On day 12 the maturing follicle releases a burst of oestrogen into the blood stream. The oestrogen travels through your blood. The gel is liquefied within 20 to 30 minutes by enzymes from the prostate gland.
This liquefaction is important for freeing the sperm so transportation may occur. The seminal plasma is left in the vagina. The protected sperm with the greatest motility travel through the layers of cervical mucus that guard the entrance to the uterus.
During ovulation, this barrier becomes thinner and changes its acidity, creating a friendlier environment for the sperm. The cervical mucus acts as a reservoir for extended sperm survival. Once the sperm have entered the uterus, contractions propel the sperm upward into the fallopian tubes. The first sperm enter the tubes minutes after ejaculation.
The first sperm, however, are likely not the fertilizing sperm. Motile sperm can survive in the female reproductive tract for up to five days. Egg transport begins at ovulation and ends once the egg reaches the uterus. Following ovulation, the fimbriated, or finger-like, end of the fallopian tube sweeps over the ovary.
Adhesive sites on the cilia, which are located on the surface of the fimbriae, are responsible for egg pickup and movement into the tube. The cilia within the tube, and muscular contractions resulting from the movement of the egg, create a forward motion. Transport through the tube takes about 30 hours. Conditions such as pelvic infections and endometriosis can permanently impair the function of the fallopian tubes, due to scarring or damage to the fimbriae.
Following ovulation, the egg is capable of fertilization for only 12 to 24 hours. Contact between the egg and sperm is random. Once the egg arrives at a specific portion of the tube, called the ampullar-isthmic junction, it rests for another 30 hours.
Fertilization — sperm union with the egg — occurs in this portion of the tube. The fertilized egg then begins a rapid descent to the uterus.
The period of rest in the tube appears to be necessary for full development of the fertilized egg and for the uterus to prepare to receive the egg.
Defects in the fallopian tube may impair transport and increase the risk of a tubal pregnancy, also called ectopic pregnancy. A membrane surrounding the egg, called the zona pellucida, has two major functions in fertilization. First, the zona pellucida contains sperm receptors that are specific for human sperm.
Second, once penetrated by the sperm, the membrane becomes impermeable to penetration by other sperm. Following penetration, a series of events set the stage for the first cell division.
With artificial insemination, sperm is often introduced directly into the cervix or uterus, so this step is bypassed. Sexual activity can cause the brain to release the hormone oxytocin 1,6 , which causes the innermost layer of the uterus to contract and push the sperm onwards 1,5,6. The uterus also has little finger like structures called cilia that help move the sperm, hopefully, towards the egg 1.
Sperm triggers an immune response when it enters the uterus 5. Also, sperm may end up going up the wrong fallopian tube. The vast majority of the time, a person only releases one egg from one ovary. That means that only one of the two fallopian tubes will have eggs, and some sperm will have gotten it wrong. Only a tiny fraction of the sperm that entered the vagina make it to the fallopian tube 5. As the fallopian tube pushes the egg towards the uterus, cilia push the sperm towards the egg.
Progesterone and estrogen influence this process by increasing the number of cilia and how fast they move 1. The egg and surrounding cells produce a chemical that attracts sperm 1,7. Sperm may be attracted to the temperature at the ovarian-end of the fallopian tube, which tends to be warmer 1,5.
As they travel through the fallopian tubes, sperm gain the ability to fertilize an egg 1. Break through a group of cells known as the cumulus oophorus that surround the egg.
The sperm dissolves these cells using an enzyme 1,7. Break through the outer membrane of the egg. The sperm essentially fuses to and digests this membrane using an enzyme 1,7. Once a sperm has penetrated an egg, this membrane changes, and becomes impenetrable to other sperm 1,7. Once it meets the egg, the nuclei from the egg and sperm merge and share their genetic material 1,7. If all this goes well, what fertilized egg becomes a zygote 1,7. The egg now contains all the genetic material it will need to become a person.
It takes about days for the fertilized egg to travel to the uterus and attach to the uterus in a process known as implantation 1,8. The egg is pushed back towards the uterus by the cilia 1.
The egg must attach to the uterus to become a viable pregnancy. While traveling to the uterus, the egg has been dividing and forming a few different structures 7. Once that barrier is broken down, the blastocyst can attach to the endometrium 1. Sometimes, though, a fertilized eggs can't make it to implantation.
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