Aims
The primary aim is to examine the relation between maternal nutrition, placental transport of
nutritional substances, and fetal blood flow distribution in normal pregnancies and in
pregnancies complicated by altered fetal growth. Specific aims:
Examine the relation between fetal glucose, amino acid and lipid consumption, and
ultrasound Doppler measures of fetal cerebral vascular resistance.
Examine the influence of extended fasting for two hours compared to a standard meal in a
group with appropriate fetal group on fetal liver blood flow and fetal cerebral vascular
resistance. The examinations will be performed at approximately 36 weeks gestation.
Examine the influence of a standard maternal meal on fetal liver blood flow and fetal
cerebral vascular resistance in pregnancies complicated by fetal growth restriction
(FGR).
Study 1: Investigator will use the 130 fetal-maternal pairs from the "placental 4 vessel
sampling method" (see below) which includes measures on fetal blood flow distribution. Some
calculations will be performed on the restricted cohort of 70 pregnancies who also includes
maternal blood flow measures.
Study 2: A limitation of investigators previous studies on the influence of glucose intake or
a regular maternal meal on fetal blood flow distribution in healthy pregnancies with
appropriate fetal growth is the lack of a control group without food intake (extended fasting
for two hours). To serve as participants own control the included participants will meet for
examinations at two different days (one with food intake and one with extended fasting)
within a few days interval. Participants will be examined in the morning and two hours after
food intake or after two hours extended fasting. The study will include 25 pregnancies with
gestational age about 36 weeks
Study 3: Investigator will include approximately 55 women (see power calculation below) with
pregnancies complicated by FGR defined as estimated birth weight (EFW) below the 3rd
percentile and/or EFW below the 10th percentile and sign of fetal Doppler blood flow
redistribution representing possible fetal compromise . Investigator hypothesize that there
will be no reduction in fetal cerebral vascular resistance (measured as change in MCA-PI from
before to after food intake). Fetal liver blood flow will also be measured.
Methods The "Placental 4 vessel sampling method" This method has recently been developed by
investigators research group and described in recent publications. In brief, blood samples
are obtained from incoming (arterial) and outgoing (venous) vessels both at the maternal and
fetal side of the placenta simultaneously during cesarean section. Samples have been taken
from women with normal pregnancies but with a range of BMI and metabolic profiles: the
physiological range group (undergoing cesarean delivery on own request).
Investigators have a complete dataset including blood sampling and fetal blood flow
measurements in the UV, DV and MCA-PI in 130 women. Further, investigators have maternal
blood flow measures in 70 of these pregnancies.
Doppler blood flow measurements Doppler blood flow measurements will be performed in the
morning immediately before (fasting state) and after a standard breakfast meal (SBM)
(approximately120 min). Internal vessel diameter (D) and time-averaged maximum velocity
(TAMX) will be measured in the straight portion of the intra-abdominal UV and at the inlet of
DV, respectively.
In the MCA Doppler velocity waveforms are sampled from the proximal part emerging from the
circle of Willis . MCA in the hemisphere near the transducer will be used unless there are
better insonation properties in the opposite hemisphere. Umbilical artery Doppler traces will
be sampled in a free-floating loop. The Doppler tracings will be used to measure fetal heart
rate (FHR). All measurements will be performed during periods of fetal quiescence.