Effect of Maternal Rest and Resting Positions on Amniotic Fluid
Condition: Pregnancy
Study type: Interventional

Summary: 
      Maternal rest in left lateral decubitus position increases fetal urine production rate which
      in turn increases the estimated amniotic fluid volume (AFV) in uncomplicated pregnancies. The
      estimated AFV increases faster at initial periods, particularly during the first, second and
      third 15 minute periods of the maternal rest in the left lateral position. Although at each
      successive 15 minute period the estimated AFV continues to increase, the increase rate is
      always less in the following period. The AFV increase curve resembles the characteristics of
      a saturation curve and finally the estimated AFV increase stops approximately at the second
      hour.

      Although maternal rest in left lateral decubitus position increased the estimated AFV in the
      previous studies, the sole effect of left lateral position or the sole effect of rest was not
      evaluated, and the results of resting in another position is not known. In addition, it is
      hard for a pregnant woman to maintain the left lateral position continuously.

      Rest in the prone position is not practical for a pregnant woman, particularly after the
      first trimester of the pregnancy and supine position may cause several hypotension related
      symptoms including nausea, anxiety, lightheadedness, shortness of breath, perspiration,
      tachycardia and urge to change position. Thus, right lateral position may be an alternative.

      The purpose of this study is to analyze the effect of maternal rest in the right lateral
      decubitus position on estimated amniotic fluid volume in comparison with the left lateral
      position. Because, in both groups the mothers rested, our secondary aim was to obtain data
      for the contribution of maternal rest to the AFI increase observed in the previous studies.
    

Detailed description: 
      In order to study the effects of maternal rest in the right or left lateral decubitus
      position on amniotic fluid index, the investigators assigned the patients into groups 1 and 2
      by using a computerized program and sealed cards (first investigator, K.Ü.). The department's
      head nurse used the sealed cards to allocate the participants into groups.

      Previous studies detected amniotic fluid index increase during maternal rest in left lateral
      decubitus position. Thus, the primary outcome of the study was to detect the same increase in
      the left lateral position, and in the right lateral position as an alternative to the former
      position. The secondary outcome was to determine the role of resting alone.

      The amniotic fluid index change values obtained in a previous study were used to perform
      power analysis. Power analysis indicated that in order to achieve an increase from the
      initial amniotic fluid index value of 153.76 ± 38.47 to the 15th minute value of 185.42 ±
      46.89 with 90% of power at one side alpha of 0.05, at least 34 women were needed in each
      group. Thus, 76 women were invited to participate in the study in order to avoid
      unpredictable errors.

      According to the predefined study design, all participants had an initial AFI measurement.
      Following the initial AFI measurements, women in Group 1 ( maternal rest in left lateral
      position) rested in the left lateral position for 15 minutes and then rested in the right
      lateral position for another 15 minutes. Women in Group 2 (maternal rest in the right lateral
      position) started resting in the right lateral position for 15 minutes and then rested in the
      left lateral position for another 15 minutes. The AFI values of both groups were measured
      before interventions, at the end of first 15 minutes and at the end of second 15 minutes.
      Depending on the study design it was impractical to blind either the observer or the
      participants. The well-being of the fetus and the mother were assessed intermittently by
      recording the fetal heart rate trace and measuring the maternal blood pressure and pulse
      rate.

      In order to avoid the inter-observer variation, a single examiner (Second investigator, M.Ç.)
      measured all AFIs by using a high resolution ultrasound apparatus (Voluson 730 Pro; General
      Electric-Kretztechnik, Zipf, Austria) equipped with a convex transducer (2-7 MHz) while the
      women were on their back in a semi-recumbent position. AFI values were calculated according
      to the technique described by Phelan et al.The vertically measured values of the four
      amniotic fluid quadrants were added to determine AFI. The same measurement was repeated
      immediately and an average of two repetitive measurements determined the AFI. Intra-observer
      variations were assessed by using the repetitive AFI measurements.
    

Intervention name(s): Maternal rest in left lateral position; Maternal rest in right lateral position
Intervention type(s): Behavioral; Behavioral
Intervention description(s): After initial amniotic fluid index measurements, the participating pregnant women were instructed to turn their left sides and rest in that position for 15 minutes before a second amniotic fluid index measurement; After initial amniotic fluid index measurements, the participating pregnant women were instructed to turn their right sides and rest in that position for 15 minutes before a second amniotic fluid index measurement
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Amniotic fluid index;; amniotic fluid volume;; intervention studies;; maternal care patterns;; mother-fetus relationships;; rest;; sonography;; transplacental exposure