Unrecognized Intrauterine Anoxia as a Cause of Fetal Death During Labor

Although impressive progress has been made in the reduction of maternal mortality there has long been recognized a lack of concomitant reduction in fetal deaths. Only recently have efforts been specifically applied to the problem of reducing fetal mortality, although general progress in medicine has lowered the neonatal death rate from 44 per 1000 live births to 24 per 1000 during the last twenty-five years. Although toxemia, prolonged labor, traumatic delivery, maternal anemia, excessive analgesia and anesthesia, and placental accidents have long been recognized as causes of intrauterine anoxia and fetal death, relatively little attention has been directed toward labor itself. The production of anoxia by over-forceful labor may well account for some of the so-called "unexplained fetal deaths in utero." Traut,' who has long been a student of placental physiology, states that oxygen saturation of fetal blood constantly diminishes toward term and in the last trimester falls from 50 to 28 per cent saturation. Such pathological changes as hemovillus degeneration may add to fetal hypoxemia and this process may be hastened by toxic states or poor nutrition, especially vitamin deficiencies. Beck' has shown that oxygen normally supplied to the fetus is relatively inadequate. The high red blood cell count of the fetus is evidence of a compensatory effort to combat this hypoxemia. The adequacy of the placenta varies with its placement in the uterus, its maturity, and the demands put upon it in labor. Knaus8 has noted in binovular twins of distinctly varying weights and size that in all instances these variations were proportionate to the placental weights. If a fetus is of excessive size, it follows that its demands upon the relatively inadequate oxygen supply at term are greater, and if gestation is prolonged, the placenta, as pointed out by McKiddie,5 becomes progressively less efficient. The stillbirth rate is often thus increased. With this physiological background it is not surprising that when there are exceedingly strong, hard, and frequent labor contractions, intrauterine anoxia may occur, leading to "unexplained deaths." Precipitate, or strong and forceful, rapid, driving labor added to the known deficiencies inherent in placental physiology can bring about fetal death in utero. Moreover, this may happen repeatedly in the same patient. Even if death does not occur,