Is mid-gestational cervical length measurement as sensitive prediction factor of preterm delivery in IVF as in spontaneous singleton pregnancies?

OBJECTIVES: To verify the relation between pregnancy duration and cervical length (CL) at 22-24 wks of spontaneous and IVF singleton gestations and to assess its predictive value for preterm delivery (< 37 wks).

MATERIAL & METHODS: CL at 22-24 wks was performed according to FMF recommendations in 344 women who conceived spontaneously and in 107 IVF singleton pregnancies. The results of CL in both groups were divided into subgroups: ≤ 29 mm, 30-34 mm; 35-39 mm; 40-44 mm; 45-49 mm and ≥ 50 mm. They were subsequently correlated with mean durations of gestation within subgroups and parameters of accuracy were calculated. Correlation and regression analysis was performed.

RESULTS: The average age of women in both groups was 28.1 y.o. (SD=4.2 years) and 33.4 y.o. (SD=4.1 years), respectively. The mean gestation age at delivery was 38.9 wks (SD=2.1 wks) vs. 37.9 wks (SD=2.3 wks) and the rate of prematurity equaled 7% vs. 15%, respectively. Regardless the method of conception there is a positive correlation between the CL and the duration of gestation. The regression analysis showed that the significant increase in pregnancy duration was correlated with CL ≥ 35 mm (correlation coefficient greater for spontaneous vs. IVF: rxy=0.418 vs rxy=0.341; p<0.001). All CL parameters of accuracy were better for spontaneous in comparison to IVF pregnancies.

CONCLUSIONS: IVF singleton pregnancy carries additional risk factors for preterm delivery. Therefore mid-gestational cervical length is less sensitive predictor than in spontaneous singleton gestations.

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