The processes listed below must occur correctly for pregnancy to result. The female’s reproductive hormone system involves complex series of relationships controlled primarily by the hypothalamus gland.
- The female must recruit sufficient follicles under the influence of FSH. Infertility results when the eggs are “too old” or loose their capacity to fertilize and develop.
- The egg(s) must grow until it is mature and ready for ovulation. Failed, or irregular, ovulation is a common cause of infertility.
- A surge of luteinizing hormone causes the egg to be “ovulated” or released from the follicle.
- During follicular maturation (eggs ripen), the body produces various hormones, such as estrogen and progesterone that cause the endometrium (lining of the uterus) to thicken and become more vascular in order to accept the developing embryo. Infertility results when the endometrium fails to develop properly, which may be due to insufficient progesterone.
- Once ovulated, the eggs must travel unimpeded through the fallopian tubes to the distal end where fertilization occurs.
- The egg must be genetically capable of fertilization and division. Tubal factor infertility can be caused by scarring from previous surgery, endometriosis, infection, congenital abnormalities, and others.
- The fertilized egg (embryo) travels to the lining of the uterus (endometrium) where it implants and continues cell division.
- The placenta must nourish the developing fetus.
- The fetus must be healthy and the mother must be able to carry the baby to term.
Dysfunction of the processes outlined above leads to infertility. Fortunately, today’s advanced technologies offer very effective means to treat most causes of infertility.