THURSDAY, Aug. 6 (HealthDay News) -- Oligohydramnios, or diminished amniotic fluid volume, is more common during the summer than the rest of the year, according to a study in the July issue of the Archives of Gynecology and Obstetrics.

Ilan Feldman, of Ben-Gurion University of the Negev in Be'er-Sheva, Israel, and colleagues performed a retrospective review of 191,558 pregnancies that delivered from 1988 to 2007, including 4,335 that were diagnosed with oligohydramnios. Summer was defined as May to August.

Of the deliveries with oligohydramnios, the researchers found that 1,553 occurred during the summer and 2,782 happened in the rest of the year. The rate of oligohydramnios during the summer was 2.5 percent and the rate was 2.1 percent during the rest of the year (odds ratio, 1.18). After controlling for variables including ethnicity, the researchers concluded that the summer season is an independent risk factor for oligohydramnios (odds ratio, 1.1).

"In the Jewish population, although there was a significant difference in the incidence of oligohydramnios during the summer months versus the rest of the year, the trend was less prominent than the one found in Bedouins. This may be due to better living conditions and less exposure to the harsh climate," the authors write.

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