Frederick R. Jelovsek
Women undergoing infertility evaluation and treatment are
concerned not only with getting pregnant, but also with whether
they will carry that pregnancy to get a healthy baby. Miscarriage
in the general population ranges from 10-20% but many of those
miscarriages occur before the women knows she is pregnant and
they just present as heavy menstrual periods. The miscarriage
rate of clinically recognized pregnancies is about 8%.
Many pregnancies that are going to result in miscarriage
(spontaneous abortion) never develop to the point where there is
a heartbeat detectable by vaginal ultrasound. In fact recent
studies have suggested that if a fetal heart beat is detected by
ultrasound between 6 and 9 weeks of menstrual age (4-7 weeks
after ovulation), then the chance of subsequent miscarriage is
only about 2%. Physicians use this 2% number to reassure women
who have had an ultrasound in which the baby's heart beat was
seen.
Keenan and coworkers looked at this data in women undergoing
infertility work ups to see if they have the same low miscarriage
rate after fetal heart beat detection as do women who do not have
infertility problems. Keenan JA, Rizvi S, Caudle MR:
Fetal loss after detection of heart motion in infertility
patients; Prognostic factors. J Reprod Med 2998;43:199-
202. In this study, they followed 231 women who were seen in
their infertility clinic and who had fetal heart beats detected
28-38 days after ovulation by ultrasound.
They found that the incidence of miscarriage was:
| Characteristic | Miscarriage Rate |
| Singleton pregnancy
| 7.7%
|
Multiple pregnancy
(twins, triplets)
| 18.0%
|
Age less than 35
(and singleton pregnancy)
| 4.9%
|
Age greater than 35
(and singleton pregnancy
| 13.4%
|
Patients who have infertility problems have mixed medical reasons
for their infertility. They also tend to be older because they
may have put off getting pregnant for various reasons.
They appear to have much higher miscarriage rates than the
general population, especially if they
are over 35 years of age or if they have a multiple pregnancy.
It is important that we are able to tell women what to expect under
various conditions.
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