1. ¹Department of Obstetrics and Gynecology, Sheba Medical Center, Tel-Hashomer, Tel-Aviv University, Tel-Aviv, Israel
2. ²Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA, USA
3. ³Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.

Correspondence: Israel Hendler, MD, Department of Obstetrics & Gynecology, Hutzel Hospital, Wayne State University, Detroit, MI, 48201 USA.

Abstract

OBJECTIVE: To compare the levels of end-tidal carbon monoxide (ETCOc) among women with and without uterine contractions in term and preterm pregnancies.

STUDY DESIGN: In all, 55 nonsmoking healthy pregnant women were enrolled. ETCOc levels were compared among women with contractions (10 preterm and 13 term) and 32 women without contractions (34–41 weeks gestation).

RESULTS: Maternal age, gravidity and parity were similar among study and control groups. ETCOc levels were significantly lower among women that had uterine contractions (0.990.38 parts per million (ppm) and 1.150.34 p.p.m. respectively), compared to women with no contractions (1.700.52 p.p.m., P<0.002). However, there was no significant difference in the ETCOc levels between women with preterm or term contractions (P=0.48).

CONCLUSIONS: Low levels of ETCOc are associated with preterm and term uterine contractions.