It is well known that airway management can be difficult during pregnancy. Increased risks for difficult intubation in pregnant women have been often reported. Thus, pregnancy is regarded as a period of high anesthesiologic risk.

Generalized weight gain is a well known factor influencing the upper airway in pregnant women. However, the modifications of the airway itself are less well documented.

The acoustic reflection method is based on the analysis of the reflection of a single transient planar wave allowing the analysis of the longitudinal cross-sectional area profile of the examined cavity. It is a noninvasive and harmless method.

The aim of the study is to evaluate by acoustic reflection method the physiological modifications of the upper airways during pregnancy.

Women enrolled in the study will undergo an acoustic recording during the first, second, and third trimester of pregnancy, as well as two days and one month after delivery. Forty pregnant women will be included in this monocentric, prospective, open labelled study.

Moreover, a single acoustic recording will be performed in 10 other pregnant women undergoing an MRI for obstetrical purpose. The estimated caliber of the upper airways by MRI and acoustic method will be compared.

Inclusion Criteria:

• Pregnant women who attend the routine ultrasound control in our institution before 14 weeks of pregnancy will be invited to participate in the study.

• Women are eligible for the study if they are:

  • healthy (no previous disease, hypertension, nor obesity),
  • 18 years or more
  • with a singleton live fetus at the routine ultrasound scan
  • with a normal pregnancy.

Exclusion Criteria:

• Pregnancy complications
• Multiple pregnancy
• High risk for preterm labor
• Underlying diseases that could interfere with the results (such as pre-existing upper airway problems) and participation.

Healthy pregnant women