What Are Repeated Miscarriages?
Any unwanted, spontaneous pregnancy loss prior to the 20th week of pregnancy is considered a miscarriage. Miscarriages are a relatively common occurrence, affecting nearly 15% of all pregnancies. However, repeat miscarriages, defined by either three consecutive first-trimester losses or two with one in the first trimester and one in the second trimester, suggests that there may be an underlying medical condition. Women experiencing repeat miscarriages should consult a recurrent miscarriage specialist to avoid further losses.
Causes of Miscarriage and Timing
Pregnancies that are confirmed only by a blood test (hCG) are considered chemical pregnancies, because the gestation is confirmed through chemical means, instead of ultrasound visualization. Clinical pregnancy is pregnancy that has reached a stage where the gestation can be seen on ultrasound. Miscarriages refer to losses of pregnancies that reached this “clinical” stage, past the chemical stage.
|Very early pregnancy loss, characterized by a positive pregnancy test (hCG) that is not maintained. A chemical pregnancy never reaches the stage where a gestational sac is seen on ultrasound examination.||Loss of a clinical pregnancy, i.e., a pregnancy loss after the fetus has reached a stage that is visible on ultrasound examination.|
In life outside of fertility treatment settings, most women do not know they had chemical pregnancies, since most women do not have pregnancy test so early in their pregnancy. During infertility treatments, however, we do diagnose these very early pregnancy losses routinely, because every treatment cycle is followed up with a very early pregnancy test. (Honest fertility programs do not consider chemical pregnancies as part of their IVF success rate statistics. Those statistics should exclusively include clinical pregnancies.)
The miscarriage of a clinical pregnancy can take place either before or after the ultrasound show a fetal heart rate. In a normally progressing pregnancy, a fetal heart should be present sometime between approximately 5.5 and 6 weeks from the first day of last menstrual period. If a pregnancy stops growing before fetal heart, or if no heart is seen by the expected time (which is usually a sign of an abnormal pregnancy), then the pregnancy is generally considered to be a “blighted ovum” or missed abortion. Whether a pregnancy loss occurs before or after fetal heart activity is quite important, because the timing of the miscarriage can provide a hint at the underlying cause (for details, continue reading.)
Norbert Gleicher, MD, leads CHR’s clinical and research efforts as Medical Director and Chief Scientist. A world-renowned reproductive endocrinologist, Dr. Gleicher has published hundreds of peer-reviewed papers and lectured globally while keeping an active clinical career focused on ovarian aging, immunological issues and other difficult cases of infertility.
Last Updated: October 8, 2018