Artery wall layer dimensions during normal pregnancy: a longitudinal study using noninvasive high-frequency ultrasound.

The vascular effects of normal pregnancy were investigated by estimating the intima and media thicknesses of the common carotid artery separately using 22-MHz ultrasound (Collagenoson, Meudt, Germany) in 57 healthy women with normal pregnancies and pregnancy outcomes, in all three trimesters and at 1 yr postpartum. A thick intima, thin media, and high intima-to-media (I/M) ratio are signs of a less healthy artery wall. Mean artery wall layer dimensions remained fairly constant during pregnancy, but the intima thickness and I/M thickness ratio appeared to improve (decrease) postpartum (P < 0.001 for both). The cardiovascular risk parameters of age, body mass index, and blood pressure in the first trimester were associated with higher I/M ratios, especially in the second trimester, whereas higher serum estradiol levels were significantly associated with a lower I/M ratio. Changes from the first to second trimesters in I/M ratio, taking into account differential changes in intima and media thickness, were significantly (P < 0.05-0.001) associated with all risk parameters tested except age, which was associated with increased intima thickness (P = 0.02). Associations with third trimester values and changes from first to third trimesters were similar but less apparent. Thus, fairly constant mean artery wall layer dimensions during pregnancy appeared to improve postpartum. However, higher age, body mass index, or blood pressure and lower serum estradiol levels in the first trimester appeared to negatively affect the artery wall, strongly suggesting that pregnancy has negative vascular effects in some women. A less likely explanation involves possible adaptation to physiological changes during and after pregnancy.