Your Biological Clock
Although a woman's fertility does start to decline after age 35, becoming pregnant is still a very viable possibility. The decline in fertility is a gradual one. There is not a sudden drop-off, where you're as fertile as the proverbial rabbit at age 34 and suddenly barren at age 35. Your body changes gradually over years. The average age for menopause is 51, so there are still many years left for childbearing, whether you are in your 30s or 40s.
According to the Mayo Clinic, female fertility peaks between age 20 and 24. From age 30 to 35, fertility is 15 to 20 percent below maximum. From age 35 to 39, it's down 25 to 50 percent, and from age 40 to 45, the decrease is 50 to 95 percent. There are several reasons why fertility can decline after age 35, including fibroids, ovulation problems, and endometriosis.
Endometriosis
Endometriosis is a condition in which the tissue that normally grows inside the uterus (the endometrium) grows outside the uterus. It attaches to the ovaries or fallopian tubes and elsewhere in the abdomen and makes it difficult for an egg to be released or travel through the tubes. When a woman gets her period, the endometrium creates the blood that is released. Women with endometriosis bleed from all their endometrial tissue, and this can become trapped in the abdomen with no way to get out. Endometriosis is often a painful condition. It can be diagnosed by laparoscopy (surgery via small openings in the abdomen). Endometriosis becomes more common after age 35. While there is no ultimate cure, there are many treatment options, including surgery, hormone treatment, and pain medication.
Ovulation Problem
Achieving pregnancy is all about eggs and the quality of those eggs. As women age, the number and quality of eggs decrease. A woman is born with all the eggs she will ever have — no new ones are created. The eggs get used up throughout your life, and they also age and experience chromosomal problems. The number of eggs remaining is called the ovarian reserve, and it's something your doctor can test. These eggs are less likely to be released from the ovary (ovulation), implant successfully in the uterus, and are more likely to be chromosomally abnormal.
How likely am I to have trouble getting pregnant?
You actually have very good odds. A report in the medical journal
Many women (up to 10 percent) experience polycystic ovarian syndrome (PCOS), in which there is an imbalance of hormones and ovulation difficulties. Additionally, women over 40 are more likely to have an imbalance of male and female hormones, which can impact ovulation.
Fibroids
According to the American Institute for Preventive Medicine, 20 to 25 percent of women over 35 have fibroids (benign tumors that grow in the uterus). African American women, women with a family history of fibroids, and women who have not been pregnant are more likely to have them. Symptoms include heavy menstrual bleeding, pain, constipation, frequent urination, and anemia. Most fibroids are small and inconsequential. However, if they are large or impinge on the uterine lining and uterine cavity, it can be difficult for a fertilized egg to implant in the uterus.
Treatment involves surgical removal of the fibroids. Another treatment option is uterine artery embolization (UAE) or uterine fibroid embolization (UFE), in which a small catheter is inserted in the artery in the groin and threaded to the uterine arteries. Small particles are injected to block the blood supply to the fibroid, causing shrinkage. This is generally performed in women who are not contemplating pregnancy, but it has been performed in women who subsequently conceived and had normal pregnancies. It may be an option when the fibroid is so large that surgical removal itself may pose a risk of loss of the uterus.
Other Reasons
Another reason for declining fertility may include cervical mucous that is less hospitable to sperm. This is tested after coitus, generally one to two days within the time ovulation is expected. Several hours following intercourse, a sample of cervical mucous is obtained. The sample is examined to see that it “stretches” at least two inches, that it forms a “fern” pattern when drying, and that there are a normal number of live sperm actively swimming forward within it. The value of this test is somewhat disputed though it appears that a poor result indicates reduced fertility.
Uterine lining is another concern. The uterine lining is sampled to determine if the corpus luteum is functioning correctly. This forms within the ovary every month and makes progesterone to prepare the lining of the uterus for a pregnancy and to maintain the pregnancy through the first nine to ten weeks. If progesterone is not made sufficiently, infertility and/or early pregnancy loss can result. To test this, a uterine biopsy is done after ovulation to assess the effect of progesterone on the uterine lining. Generally, several tests must be performed to confirm the diagnosis, as every woman has occasional cycles in which the corpus luteum is insufficient. Treatment can include progesterone supplements during the luteal, or second, phase of the cycle or ovulation drugs to make ovulation stronger and the corpus luteum in that cycle more resilient. Some physicians prefer to do an ultrasound to evaluate the uterine lining.
