Initial Miscarriage Linked to Greater Risk for Obstetric Complications


Test Questions


1. In the previous study by Jivraj and colleagues, recurrent miscarriage was associated with a higher risk for all of the following outcomes in subsequent pregnancies except:

  • Diabetes
  • Preterm delivery
  • Perinatal loss
  • Cesarean delivery
2. In the current study by Bhattacharya and colleagues, rates of all of the following outcomes in subsequent pregnancies were higher in the miscarriage cohort vs the successful pregnancy and primigravid cohorts except:

  • Elective cesarean delivery
  • Preterm delivery
  • Threatened miscarriage
  • Induction of labor

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Answers / Explanations:


1. In the previous study by Jivraj and colleagues, recurrent miscarriage was associated with a higher risk for all of the following outcomes in subsequent pregnancies except:

[HIDE]
Answer: Diabetes

A previous study found that recurrent miscarriage was associated with higher rates of preterm delivery, small-for-gestational-age infants, perinatal loss, and cesarean delivery in subsequent pregnancies. However, recurrent miscarriage did not have a significant effect on the risks for hypertension or diabetes during later pregnancies.
[/HIDE]
2. In the current study by Bhattacharya and colleagues, rates of all of the following outcomes in subsequent pregnancies were higher in the miscarriage cohort vs the successful pregnancy and primigravid cohorts except:

[HIDE]Answer: Elective cesarean delivery

In the current study, women with a miscarriage in their first pregnancy experienced higher rates of preterm delivery, threatened miscarriage, and induction of labor in subsequent pregnancies vs women who had a successful delivery and women in their first pregnancy followed up prospectively. However, rates of elective cesarean delivery were similar between groups.[/HIDE]

For Your reference:


Initial Miscarriage Linked to Greater Risk for Obstetric Complications


December 18, 2008 Initial miscarriage is associated with a higher risk for obstetric complications in the next pregnancy, according to the results of a retrospective cohort study reported in the December issue of the BJOG: An International Journal of Obstetrics and Gynaecology.

"Miscarriage or spontaneous pregnancy loss before 24 completed weeks of gestation is estimated to affect 1015% of pregnancies," write S. Bhattacharya, from the Dugald Baird Centre for Research on Women's Health, Aberdeen Maternity Hospital in Aberdeen, United Kingdom, and colleagues. "While a spontaneous miscarriage is distressing at any time, it is particularly so if it occurs in the first pregnancy. Previous work has focused on the risk of further miscarriage in these women, but there have been few attempts to study obstetric and perinatal outcomes in subsequent pregnancies that progressed beyond 24 weeks."

The goal of this study was to evaluate pregnancy outcomes in women after an initial miscarriage and to compare them with women with 1 previous successful pregnancy and with primigravid women. The study cohort consisted of all women living in the Grampian region of Scotland who had a pregnancy recorded in the Aberdeen Maternity and Neonatal Databank between 1986 and 2000.

The study endpoints included maternal outcomes of preeclampsia, antepartum hemorrhage, threatened miscarriage, malpresentation, induced labor, instrumental delivery, cesarean delivery, postpartum hemorrhage, and manual removal of placenta, as well as perinatal outcomes of preterm delivery, low birth weight, stillbirth, neonatal death, and Apgar score at 5 minutes.

Of 1561 women identified who had a first miscarriage, 1404 miscarried in the first trimester and 157 in the second trimester. The 2 comparison groups consisted of 10,549 women who had had a previous live birth and 21,118 primigravid women.

Compared with women who had had a previous live birth, the miscarriage group had a higher risk for preeclampsia (adjusted odds ratio [adj OR], 3.3; 99% confidence interval [CI], 2.6 - 4.6), threatened miscarriage (adj OR, 1.7; 99% CI, 1.5 - 2.0), induced labor (adj OR, 2.2; 99% CI, 1.9 - 2.5), instrumental delivery (adj OR, 5.9; 99% CI, 5.0 - 6.9), preterm delivery (adj OR, 2.1; 99% CI, 1.6 - 2.8), and low birth weight (adj OR, 1.6; 99% CI, 1.3 - 2.1).

Compared with primigravid women, the miscarriage group had a higher risk for threatened miscarriage (adj OR, 1.5; 99% CI, 1.4 - 1.7), induced labor (adj OR, 1.3; 99% CI, 1.2 - 1.5), postpartum hemorrhage (adj OR, 1.4; 99% CI, 1.2 - 1.6), and preterm delivery (adj OR, 1.5; 99% CI, 1.2 - 1.8).

"An initial miscarriage is associated with a higher risk of obstetric complications," the study authors write. "Many of these risks, however, are no higher than those in primigravidae. Thus, women who have an initial early pregnancy loss behave like 'virtual primigravidae' in their next pregnancy not only in terms of their labour and delivery characteristics but also with regard to pregnancy complications and neonatal outcomes."

Limitations of this study include observational design, retrospective nature, possible selection bias, tertiary referral center setting, limited generalizability, and statistical issues involving multiple comparisons with use of a large data set.

"Women with an initial miscarriage are at increased risk of some obstetric and perinatal complications in comparison with women who have a successful initial pregnancy," the study authors conclude. "While overall risks are less pronounced in comparison with primigravid women, the risks of threatened miscarriage, induced labour and postpartum haemorrhage are higher in women with an initial miscarriage. These incremental risks are small and may not be clinically significant."

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Clinical Context

Recurrent miscarriage, which is generally defined as 3 or more previous miscarriages, is associated with negative outcomes of subsequent pregnancies. A previous study by Jivraj and colleagues, which was published in the January 2001 issue of Human Reproduction, found that women with a history of recurrent miscarriage had higher rates of preterm delivery, small-for-gestational-age infant, perinatal loss, and cesarean delivery vs a control group who did not have a history of recurrent miscarriage. However, a history of recurrent miscarriage did not have a significant effect on the risks for hypertension or diabetes.

The current retrospective cohort study examines whether a miscarriage in the initial pregnancy is also associated with negative outcomes in subsequent pregnancies.



Study Highlights

  • Study data were drawn from the Aberdeen Maternity and Neonatal Databank, which records data from all pregnancies in 1 region of Scotland. Previous reviews have demonstrated that information in the databank is more than 90% accurate.
  • The current study focused on women with a singleton pregnancy between 1986 and 2000. Women with fetal congenital malformations discovered on ultrasound examination were excluded from the research.
  • The test group included women with a spontaneous miscarriage before 24 weeks of gestation. These women were compared with women with a live birth beyond 24 weeks of gestation in their first pregnancy (successful pregnancy cohort) and women with a continuing pregnancy beyond 24 weeks (primigravid cohort).
  • Pregnancy data for 5 years after their initial pregnancy were examined for women with a miscarriage and a previous successful pregnancy.
  • The main outcomes of the study were maternal and perinatal results in the miscarriage, successful pregnancy, and primigravid cohorts.
  • 1561 women were included in the miscarriage cohort, and 10,549 and 21,118 women comprised the successful pregnancy and primigravid cohorts, respectively.
  • Compared with the successful delivery group, women with a miscarriage were younger and were more likely to smoke. However, women with a miscarriage were generally older than the primigravid subjects. Women with a miscarriage had the highest mean body mass index among the 3 groups (25.53 kg/m2).
  • Compared with women with a successful delivery, women with an initial miscarriage experienced a higher risk for preeclampsia (adj OR, 3.3), threatened miscarriage (adj OR, 1.7), induction of labor (adj OR, 2.2), and instrumental vaginal delivery (adj OR, 5.9).
  • In addition, women in the miscarriage cohort had higher risks for preterm delivery before 34 weeks of gestation (adj OR, 2.1) and birth weight less than 2500 g (adj OR, 1.6).
  • Women with an initial miscarriage had a lower rate of subsequent elective cesarean delivery vs women with a successful delivery.
  • Women with a miscarriage were similar to primigravid women regarding pregnancy and perinatal outcomes. However, women in the miscarriage group experienced significantly higher risks for threatened miscarriage, induction of labor, and postpartum hemorrhage. Preterm delivery was also more common in women with miscarriage vs primigravid women.
  • Rates of elective cesarean delivery were similar when comparing the miscarriage and primigravid groups.
  • There was little difference in the main study outcomes in a subgroup analysis comparing women with first-trimester miscarriages vs women with second-trimester miscarriages.
Pearls for Practice

A previous study found that recurrent miscarriage was associated with higher rates of preterm delivery, small-for-gestational-age infants, perinatal loss, and cesarean delivery in subsequent pregnancies. However, recurrent miscarriage did not have a significant effect on the risks for hypertension or diabetes during later pregnancies.

In the current study, women with a miscarriage in their first pregnancy experienced higher rates of preterm delivery, threatened miscarriage, and induction of labor in subsequent pregnancies vs women who had a successful delivery and women in their first pregnancy followed up prospectively. However, rates of elective cesarean delivery were similar between groups.


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