Hormones are secreted by glands in the endocrine system. During puberty, hormones create changes in physical and emotional characteristics.
Some women have difficulty becoming pregnant because they don't produce enough FSH to allow their eggs to mature. Fertility drugs contain FSH and LH, which stimulate eggs to mature in the ovary.
Fertility treatments increase a woman's chance of becoming pregnant, although the treatment may not always work. On the other hand, because the treatment boosts the production of mature eggs, it increases the chance of twins or triplets. Multiple pregnancies carry a risk of complications, and may lead to premature or underweight babies.
If a couple are having difficulty conceiving a child because there are issues with the quality of the man's sperm, or a woman has blocked oviducts, then IVF can be used.
The development of microscopy techniques have allowed IVF treatments to be developed further.