The Increase of Blood Flow in the Fetal Middle Cerebral Artery Correlates With the Onset of Labor at Term

Abstract

The objective of this cohort study is to evaluate the relationship between blood flow resistance in the fetal middle cerebral artery (MCA) and the beginning of spontaneous labor. A group of consecutive women (n = 664) with a singleton pregnancy was submitted to Doppler examination of fetal MCA between 24 and 41 weeks' gestation (median, 35 weeks). The study population was later divided into 2 groups according to the MCA pulsatility index (PI), expressed in multiples of the median (MoM) for each gestation week. The median time elapsed between the Doppler examination and the onset of spontaneous labor (which eventually occurred in 302 women, of whom 291 were at term) was significantly shorter in the group with MCA PI <0.74 MoM (5.5 days; interquartile interval, 2-10 days) than in the group with MCA PI ≥0.74 MoM (22.5 days; interquartile interval, 5-37.5 days; P < .001). Survival analysis and Cox regression confirmed that the MCA PI was independently associated with the number of days elapsed from Doppler to spontaneous labor (P < .001; Exp[B], 2.77; 95% confidence interval, 1.95-3.90) after correction for birth weight and umbilical artery PI. The present data suggest that, at term of pregnancy, a gestation-independent decrease of fetal cerebral vascular resistance precedes the onset of spontaneous labor.

Keywords

Labor Doppler ultrasound middle cerebral artery resistance index.

References

Botsis D. , Vrachnis N. , Christodoulakos G. Doppler assessment of the intrauterine growth-restricted fetus. Ann N Y Acad Sci. 2006;1092:297-303.

Bahlmann F. , Reinhard I. , Krummenauer F. , Neubert S. , Macchiella D. , Wellek S. Blood flow velocity waveforms of the fetal middle cerebral artery in a normal population: reference values from 18 weeks to 42 weeks of gestation. J Perinat Med. 2002;30:490-501.

Nicolaides K. , Rizzo G. , Hecker K. , Ximenes R. Doppler in Obstetrics. Diploma in Fetal Medicine Series. ISUOG Educational Series; 2002. http://www.centrus.com.br/DiplomaFMF/SeriesFMF/doppler/index-doppler.htm.

Gadelha Da Costa A. , Mauad Filho F. , Spara P. Barreto Gadelha E. , Vieira Santana Netto P. Fetal hemodynamics evaluated by Doppler velocimetry in the second half of pregnancy. Ultrasound Med Biol. 2005;31:1023-1030.

Gadelha-Costa A. , Spara-Gadelha P. Filho FM , Gadelha EB Hemodynamic changes in the fetal arteries during the second half of pregnancy assessed by Doppler velocimetry. Eur J Obstet Gynecol Reprod Biol. 2007;132:148-153.

Hsieh,YY Chang CC , Tsai HD , Tsai CH Longitudinal survey of blood flow at three different locations in the middle cerebral artery in normal fetuses. Ultrasound Obstet Gynecol . 2001; 17:125-128.

Medina Castro N. , Figueroa Diesel H. , Hernandez Andrade E. Normal reference values of the pulsatility index and peak systolic velocity in the fetal middle cerebral artery during normal pregnancy. Ginecol Obstet Mex. 2006;74:376-382.

Maesel A. , Sladkevicius P. Valentin L. , Marsal K. Fetal cerebral blood flow velocity during labor and the early neonatal period . Ultrasound Obstet Gynecol. 1994;4:372-376.

Yagel S. , Anteby E. , Lavy Y. , et al. Fetal middle cerebral artery blood flow during normal active labour and in labour with variable decelerations. Br J Obstet Gynaecol. 1992;99: 483-485.

10.

Noordam MJ , Heydanus R. , Hop WC , Hoekstra FM , Wladimiroff JW Doppler colour flow imaging of fetal intracerebral arteries and umbilical artery in the small for gestational age fetus. Br J Obstet Gynaecol. 1994;101: 504-508.

11.

Cynober E. , Hamami M. , Cabrol D. , Uzan M. , Jeny R. Preliminary study on the variability of the fetal cerebral velocimetry in various vessels of the Circle ofWillis.J Gynecol Obstet Biol Reprod (Paris). 1992;21:677-682.

12.

Gosling RG , King DH Ultrasound Angiology. New York, NY: Churchill-Livingstone; 1975.

13.

Vyas S. , Campbell S. , Bower S. , Nicolaides KH Maternal abdominal pressure alters fetal cerebral blood flow. Br J Obstet Gynaecol. 1990;97:740-742.

14.

Yudkin PL , Aboualfa M. , Eyre JA , Redman CW , Wilkinson AR New birthweight and head circumference centiles for gestational ages 24 to 42 weeks. Early Hum Dev. 1987;15: 45-52.

15.

Mari G. , Hanif F. , Treadwell MC , Kruger M. Gestational age at delivery and Doppler waveforms in very preterm intrauterine growth-restricted fetuses as predictors of perinatal mortality. J Ultrasound Med. 2007;26:555-559.

16.

Mari G. , Zimmermann R. , Moise KJ Jr , Deter RL Correlation between middle cerebral artery peak systolic velocity and fetal hemoglobin after 2 previous intrauterine transfusions. Am J Obstet Gynecol. 2005;193:1117-1120.

17.

Florio P. Torricelli M. , Galleri L. , et al. High fetal urocortin levels at term and preterm labor. J Clin Endocrinol Metab. 2005;90:5361-5365.

18.

Smith R. , Nicholson RC Corticotrophin releasing hormone and the timing of birth. Front Biosci. 2007;12:912-918.

19.

Petraglia F. , Florio P. Benedetto C. , et al. Urocortin stimulates placental adrenocorticotropin and prostaglandin release and myometrial contractility in vitro. J Clin Endocrinol Metab. 1999;84:1420-1423.

20.

Leitch IM , Boura AL , Botti C. , Read MA , Walters WA , Smith R. Vasodilator actions of urocortin and related peptides in the human perfused placenta in vitro. J Clin Endocrinol Metab. 1998;83:4510-4513.

21.

Florio P. Torricelli M. , De Falco G. , et al. High maternal and fetal plasma urocortin levels in pregnancies complicated by hypertension. J Hypertens . 2006;24:1831-1840.

22.

Rademaker MT , Charles CJ , Espiner EA , et al. Beneficial hemodynamic, endocrine, and renal effects of urocortin in experimental heart failure: comparison with normal sheep. J Am Coll Cardiol. 2002;40:1495-1505.

23.

Westergaard HB , Langhoff-Roos J. , Lingman G. , Marsal K. , Kreiner S. A critical appraisal of the use of umbilical artery Doppler ultrasound in high-risk pregnancies: use of meta-analyses in evidence-based obstetrics. Ultrasound Obstet Gynecol. 2001;17:466-476.