19.1 The surfactant test for fetal maturity

The surfactant test is a simple way of estimating the maturity of a baby. It is seldom needed in the developed world, where the length of gestation can usually be obtained from a pelvic examination early in pregnancy, or by an ultrasound scan. Unfortunately, this does not apply in the developing world, where the surfactant test still has a useful place. It is not infallible, so don’t rely on it alone— use it in conjunction with an estimate of gestation by dates, and an estimate of the baby’s size. It is a test for the surfactant which his alveolar cells secrete, and which is necessary for the expansion of his lungs immediately after birth. If they don’t expand, he develops the respiratory distress syndrome, so the test is a measure of the extent to which he is at risk from this.

Figure 19.1: THE SURFACTANT TEST normally becomes positive at 36 weeks, so it is a good sign that a baby is mature enough to induce.

The test normally becomes positive at 36 weeks, so it is a good sign that he is mature enough to induce. Obtaining amniotic fluid is easy and safe for him and his mother, and is no more painful than an intramuscular injection. Rare complications include rupture of the membranes and injury to his head.