Correlation of Uterine Blood Flow in the First Trimester of Pregnancy and Birth Weight at Term in High Altitude.

UNLABELLED: Villamonte-Calanche, Wilfredo, Marco Antonio Salazar-Zegarra, Franklin Miranda-Solis, and María Jerí-Palomino. Correlation of uterine blood flow in the first trimester of pregnancy and birth weight at term in high altitude. High Alt Med Biol. 00:00-00, 2026.

OBJECTIVE

To determine the correlation between total uterine artery flow (UtAQ) at the end of the first trimester of pregnancy and birth weight (BW) at term at 3,400 m altitude.

METHODS

Prospective study, conducted at 3,400 m altitude in 210 women who underwent routine ultrasound evaluation. The inclusion criteria were singleton pregnancy between 11 and 14 weeks + 1 day, crown-rump length between 45 and 84 mm, born and raised at high altitude (native), and without pathology. The outcome was BW, expressed as a Z score. Variables such as UtAQ, uterine artery (UtA) diameters, age, body mass index, and mean arterial pressure, among others, were evaluated.

RESULTS

After applying the inclusion criteria, 203 pregnant women were evaluated, out of a total of 210 women. The average diameter of UtA was 0.27 cm, and the total bilateral UtA blood flow was 305.8 ml/min. A significant correlation was found between BW and UtAQ (rho = 0.15, p = 0.033), with a higher association for the left UtA (rho = 0.19, p = 0.007). Similarly, BW was positively correlated with the average diameter of the UtAs (r = 0.21, p = 0.003) and the association was stonger for the left UtA (r = 0.19, p = 0.006).

CONCLUSION

In low-risk singleton pregnancies among native women living at high altitude, a correlation was observed between UtAQ and term BW, with the highest association found between BW and the diameter and UtAQ of the left UtA.