Tehran University Medical Journal

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The present research is a quasi-experimental prospective study to determine usefulness of stripping the fetal memberanes at term for preventing of postterm pregnancy. 212 pregnant women with firm gestational dates entered the study, 112 underwent stripping of the membranes and 100 controls did not. The difference between the number of patients who advanced beyond term (>290 days) was statistically significant between groups (P<0.01). The mode of delivery and neonatal APGAR score were similar in both groups.

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Background: There is dearth of reports from Iran regarding the prevalence of postterm pregnancy and its complications. The present study was conducted to evaluate the prevalence, management and outcome of prolonged pregnancies.

Methods: This cross-sectional study included data from the hospital records of all women referred to Shariati Hospital, Tehran, from 2001 to 2002 with pregnancies of more than 40 weeks in duration. Pregnancies ≥40-42 weeks were considered postdate and those more than 42 weeks postterm pregnancy. The data compiled from the hospital records were subjected to t, χ² and Mann-Whitney U tests.

Results: Of the 1500 deliveries in this hospital, 98 patients were included in this study, 66.3% of whom were nullipara and 33.7% multipara. The prevalence of postterm pregnancy was estimated to be 3.3%. Cervix dilation of 2 cm or less on admission occurred in 65 women (73.3%). The mean Bishop score was 4.31. Of the 62 fetuses that underwent assessment tests, 54 (87.1%) were normal. The median time between the last test and induction of labor was 2.1 days, and 2.6 days for cesarean deliveries, which was not a significant difference (P=0.6). Cervical ripening with misoprostrol was performed in 36 cases (36.7%) and was successful in 18 cases. In this group, the median time for cervical ripening in multiparas was significantly less than nulliparas (4 vs. 7 hrs, P=0.004). Women not subjected to cervical ripening had a higher cesarean rate than those who did undergo cervical ripening (74.7% vs. 66.1%), although this difference was not significant (P=0.9). Vaginal and cesarean delivery rates showed no significant difference between cases that underwent induction with oxytocin and those subjected to cervical ripening with misoprostol (P=0.9). The mean Apgar score was 9.5, with all scores above 6. There were no cases of neonatal hypoglycemia, hypocalcemia, NICU admission or prenatal death. The mean nursery stay was 1.84 days with a range of 1-8 days.

Conclusions: The prevalence of postterm pregnancies was 3.3% in this study, due in part to erroneous estimation of gestational age. Sonography exam in the first half of pregnancy can provide a better estimation of gestational age and thereby reduce the rate of postterm pregnancy. Cervical ripening and induction of labor shorten the duration of pregnancy however, whether it has any beneficial effect on neonatal outcome remains controversial.

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Background: Approximately 10 percent of all pregnancies continue to 42 weeks'gestation. The true prevalence of pregnancies lasting longer than 41 or 42 weeks'gestation has been difficult to establish because many such diagnoses occur as a result of an inability to accurately establish time of conception. Several studies indicate that menstrual dating is often inaccurate and can lead to induction of labor for a presumed but inaccurate diagnosis of postterm pregnancy. It is now widely accepted that a more precise method of determining gestational age is the first trimester measurement of crown-rump length of the fetus.

Methods: We carried out a cross- sectional study on patients who were referred for a prenatal care to Arash hospital, Medical Sciences/University of Tehran. Women in the first trimester of pregnancy who presented to the center during the study period with precise  date of last menstrual period were eligible to enroll. They underwent an ultrasound dating scan between 8 and 12 weeks, measuring crown-rump length. The estimated date of delivery (EDD) was changed if there was a discrepancy of more than 5 days from the gestation, calculated from the last menstrual period (LMP). For the remaining women (no-scan group), gestation was determined using the LMP. Data were analyzed using SPSS, 11. Statistical significance was assessed with Chi-square, student t-test and Anova, using a significance threshold of < 0.05.

Results: Of 217 women who were enrolled, 10.6% of the patients who underwent an ultrasound dating scan were postdate versus 3.7% of the patients whose gestational age calculated from LMP (p=0.005).

Conclusions: The application of first trimester sonographic measurement of crown-rump length of the fetus results in a significant reduction of the diagnosis of postterm pregnancies.