Without estrogen, the development of a healthy child simply would never occur. In about 10 to 20 per cent of first-time mothers, all that extra estrogen continues to stimulate the growth of uterine tissue even after the child is born. The uterus can grow "lumps" that can block the cervix, so sperm cannot enter the womb, or block the ovaries, so the egg cannot be released when it is time for ovulation. These tough, fleshy growth, known as fibroids, or leiomyomas, are enough to prevent conception. Uterine fibroids come in various shapes and sizes. More often than not, they are so small that they only show up after a pelvic exam or ultrasound. However, sometimes uterine fibroids grow so large that they cause a "false pregnancy," filling the womb with fibrous tissue.
Avoiding high-estrogen birth control pills and high-tech surgical procedures, such as laser ablation, can literally clear the way for conception. Sometimes infertility issues focus on the male partner. Exposure to cigarette smoke, cleaning solvents, paint, petrochemicals, herbicides, and pesticides can lower sperm counts. A painful hernia known as testicular torsion can keep the sperm in the testes, and sexually transmitted diseases (especially Chlamydia) or even urinary tract infections can lower male fertility. Treating male infertility to enhance sperm quality in these cases requires avoiding contact with environmental toxins and treatment of infection. Another issue in secondary infertility, especially after the age of 40, is age.
Even when conception is possible, thickening of the uterus or the cumulative effects of surgical procedures lower the chances for the fertilized egg to implant itself so it can become a growing embryo. Conception requires both man's sperm count and the woman's fertility to be at their peak when the woman ovulates, so timing sexual intercourse is yet another consideration in treating secondary infertility.