Miscarriage & Recurrent Pregnancy Loss
Recurrent pregnancy loss (RPL) is defined by two or more failed pregnancies. Although about one-fourth of known pregnancies result in miscarriage, the U.S. Department of Health and Human Services estimates that less than 5 percent of women experience two consecutive miscarriages, while one percent experience three or more.
The good news is that about two-thirds of women who have suffered unexplained RPL have a successful pregnancy in subsequent efforts. A healthy lifestyle can help improve those odds: getting moderate exercise, controlling weight, quitting smoking, and reducing alcohol and caffeine intake may be beneficial in avoiding RPL.
Of course, the emotional impact of recurrent pregnancy loss can be significant. Psychological counseling may help a couple cope with grief, anger, isolation, fear, and helplessness common after repeated miscarriages.
Pinpointing the cause of repeated miscarriages can be difficult. In more than half of couples with recurrent pregnancy losses doctors are unable to find a specific reason. Yet there are a number of factors at play.
Common Factors in RPL
Age increases the chance of a miscarriage. More than one-third of all pregnancies after age 40 end in miscarriage. Chromosomes play a factor in such cases of advanced maternal age, as most embryos that end in miscarriage for these women carry an abnormal number of chromosomes.
Genetic and chromosome factors figure prominently in RPL. For both natural and assisted conception, chromosomally abnormal embryos have a low rate of implantation in the uterus.
In humans there are 23 pairs of chromosomes, which contain DNA (deoxyribonucleic acid), the blueprint of life. DNA provides the codes for the proteins that make up every cell in the human body.
Sperm and eggs contain only 23 single chromosomes, one from each chromosome pair). During fertilization, the embryo receives one chromosome of each pair from each parent resulting in a normal male (46,XY) or a normal female (46,XX).
But if either the sperm or the egg carries a gene mutation the embryo might carry a genetic disorder. Fortunately, chromosome analysis of the parents’ blood has shown an inherited genetic cause in less than 5 percent of those couples.
More commonly, studies have indicated that 60 percent or more early miscarriages may be caused by a random chromosomal abnormality, usually a missing or duplicated chromosome. Couples with specific chromosome defects may benefit from pre-implantation genetic diagnosis (PGD) in conjunction with in vitro fertilization (IVF).
Hormonal abnormalities may play a role if there is a shortage of progesterone, a hormone produced by the ovary after ovulation – although there is controversy about whether low progesterone levels, often called luteal phase deficiency, may cause repeated miscarriages. Treatments may include ovulation induction, progesterone supplementation or injections of human chorionic gonadotropin (hCG), but there is no evidence to support the effectiveness of these treatments.
Uterine abnormalities may be found in approximately 10 to 15 percent of women who have suffered recurrent pregnancy loss. Congenital uterine abnormalities include a double uterus, uterine septum, and a uterus in which only one side has formed. Other factors include acquired abnormalities such as Asherman’s syndrome (scar tissue in the uterine cavity), uterine fibroids, and possibly uterine polyps. Some of these conditions can be corrected through surgery.
Poorly controlled diabetes increases the risk of miscarriage. Women with insulin resistance, obese women and women with polycystic ovarian syndrome (PCOS) suffer higher rates of miscarriage. Unfortunately, there is not enough evidence to know if medications that improve insulin sensitivity lower miscarriage risks in women with PCOS.
Male factor infertility may affect embryo development and possibly increase miscarriage risk, increasing evidence suggests. The theory is that abnormal integrity (intactness) of sperm may play a role, although the evidence is still preliminary, and doctors aren’t certain how often sperm defects contribute to recurrent miscarriage.
Thrombophilia is the propensity to develop serious blood clots (thrombosis), and women with this inherited disorder may also increase the risk of fetal death in the second half of pregnancy. However, there is no proven benefit for testing or treatment of women with thrombophilias and recurrent miscarriage in the first half of pregnancy.
Antiphospholipid syndrome (APS or APLS) can cause RPL for 3 to 15 percent of women who have suffered RPL. APS is also a coagulation disorder that causes thrombosis in both arteries and veins and can lead to miscarriages, pre-term delivery or severe preeclampsia – a rapidly progressive condition characterized by high blood pressure and the presence of protein in the urine; preeclampsia can be a serious threat to both maternal and infant health.
Blood tests may identify women with antiphospholipid syndrome, A second blood test performed at least six weeks later confirms the diagnosis. In women with high levels of antiphospholipid antibodies, pregnancy outcomes are improved by the use of aspirin and heparin.