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Early menopause
Early depletion of ovarian follicles before age 35
Although the cause is unknown, certain conditions are associated with early menopause, including immune system diseases, radiation or chemotherapy treatment, and smoking
Other Causes
Temporary infertility may occur with the use of certain medications. In most cases, fertility is restored when the medication is stopped.
Disorders of the thyroid gland, either too much thyroid hormone (hyperthyroidism) or too little (hypothyroidism), can interrupt the menstrual cycle and cause infertility.
Certain cancers particularly female reproductive cancers often severely impair female fertility. Both radiation and chemotherapy may affect a woman's ability to reproduce. Chemotherapy may impair reproductive function and fertility in men and women.
Medical conditions associated with delayed puberty or amenorrhea, such as Cushing's disease, sickle cell disease, HIV/AIDS, kidney disease and diabetes, can affect a woman's fertility.
Excessive caffeine consumption reduces fertility in the female.
Development Problems
If the egg is too 'hard', then the embryo cannot hatch out of the zona pellucida and it dies.
To fix this problem, scientists can make a tiny hole in the egg to give it a head start.
Recall fertilization is associated with spermegg interaction, which begins after sperm capacitation. A sperm first penetrates the cumulus oophorus (a), consisting of cumulus cells (somatic cells from the ovarian follicle) embedded in an extracellular matrix (ECM). The sperm then contacts the zona pellucida (b), where the acrosome reaction is triggered by ZP3. Acrosome-reacted sperm penetrate the zona pellucida, enter the perivitelline space, then adhere to (c) and fuse with (d) the plasma membrane of the egg. The egg has extruded the first polar body (PB1) and progressed to metaphase II. In most mammals, spermegg fusion triggers the completion of meiosis. This model is based on in vitro studies of gamete interactions and is consistent with in vivo fertilization, which occurs in the oviduct.
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