Effect of chronic intermittent stress on rat pregnancy and postnatal development

The present study evaluates the effect of exposure to chronic intermittent cold-swimming stress on body weight gain of pregnant rats and subsequent development of the offsprings after birth, till peripubertal stage. When stress was administered during the first half (1-11 days) of gestation, weight gain of pregnant rats was significantly lower at the 9th and 11th days (P <0.05 vs. control, respectively). No differences of weight gain in comparison with control rats were found at term gestation in pregnant rats exposed to stress continuously. Similarly, stress administered, starting from 12th day till term gestation, had no effect on weight gain. Even though weight gain of pregnant rats during the second half of pregnancy in group stress 1-11 was restored to normal values, a high mortality rate of neonates 1, 2 and 3 weeks after birth was found in this group (P <0.02, 0.01 and 0.001 vs. controls). There was no significant difference between stressed and control groups with respect to the number or body weight of litters, as well as weight gain of neonates during the first 21 days of life. In addition, in offsprings from all stressed groups, a high number of small for date animals was found after 14 days of life, and 74.4% of these small for date animals died during the peripubertal period. The present data demonstrate that the exposure to stress in utero may induce damaging effects on postnatal development.