Intrauterine resuscitation during term labor by maternal hyper oxygenation: a pilot study.

Perinatal asphyxia is one of the four main causes of perinatal morbidity and
mortality in the Netherlands. Small human studies of poor quality do indicate
that additional oxygen supplied to the mother in case of fetal distress
improves fetal condition during labor. In the USA maternal hyperoxygenation in
case of fetal distress is common practice and recommended by the American
College of Obstetricians and Gynecologists. However, the British guideline
recommends not to use additional oxygen for fetal distress because of the lack
of randomized studies proving its beneficial effect and potentially harmfull
effect of increased free-radical production. The Dutch guideline did not
propose any recommendation yet. Several reviews conclude that there is an
urgent need for a randomized controlled trial investigating the effect of
maternal hyperoxygenation on fetal condition. We hypothesise that the
beneficial effects on fetal oxygenation outweighs the potential increase in
free-radical production.

To investigate the effect of maternal hyperoxygenation with 100% in the second
stage of labor and in the presence of abnormal fetal heart rate (FHR) patterns
on fetal condition, instrumental delivery rate and free radical production. In
case a positive effect on FHR pattern is shown, we will use the data obtained
from this study to design a larger, multicenter RCT to investigate the effect
on umbilical cord pH and/or Apgarscore.

Randomized controlled trial in a tertiary hospital in the Netherlands.

In case of suboptimal or abnormal FHR patterns (FIGO classification) during the
second stage of labor, 100% oxygen is applied to the mother by a
non-rebreathing mask until delivery.

Continuous FHR monitoring generally takes place through a transvaginal lead
attached to the fetal head. This is common practice in all clinical deliveries.
The non-rebreathing mask fits tight to the nose and mouth which may cause some
discomfort to the parturient. High levels of inspired oxygen may cause
reversible vasoconstriction in the mothers brain of approximately 10%. This is
not expected to cause any harm. Besides, the amount of free oxygen radicals
will increase in the maternal blood. We do not expect this to cause any harm
due to the mature anti-oxygen sytem in the adult. We expect the fetus to profit
from maternal hyperoxygenation by improved pH levels and a decreased risk on
prolonged fetal hypoxia potentially resulting in perinatal asphyxia. In the
fetal blood the amount of free oxygen radicals may increase as well. Neonatal
resuscitation with 100% oxygen may lead to an increased risk of fetal
bronchopulmonary disease and retinopathy, especially in premature infants.
However, in this study preterm deliveries are excluded. Besides, the increase
in fetal pO2 due to maternal hyperoxygenation will never reach the increase as
a result of direct application of 100% oxygen to the fetus.

Besides we hypothesise that less interventions to immediately deliver the
fetus, such as episiotomy, assisted vaginal delivery or caesarean sections will
be needed. Both mothers and foetuses will profit from this effect.