The journal article that caught my attention this week was a presentation of the distribution of singleton preterm birth in Australia from 1986 to 2014.1 It caught my eye because it showed that over time, the rates of preterm birth increased. But what was interesting to me was the trade-off; as preterm birth was increasing the stillbirth rate decreased.
There are many factors that contribute to preterm birth, but the breakdown by maternal and fetal condition suggest that preterm birth rates were increasing as a natural consequence of preventing stillbirth. We have learned enough to understand when a fetus is at high risk for stillbirth, but we are still limited in our ability to prevent it. When the other prevention tools fail, scheduled preterm birth (iatrogenic means caused by the physician/midwife) is the only tool left.
This leaves me conflicted. While I am glad that we have made advancements in the care of preterm birth I am frustrated that we are still so limited in our prevention of stillbirth that preterm delivery becomes a “good” choice. And while there were increases in preterm birth among the high risk groups, the rates were still low; less than 20% of women with hypertensive disorders and less than 6% of women whose fetus was small for gestational age. This means for most women in South Australia, even with problems that make them high risk for stillbirth, the pregnancy ends full term.
What about the USA?
That article was from a single state, South Australia. Internationally, we know the experience of South Australia is not unique. Higher rates of prelabor cesarean delivery are associated with lower perinatal death rates and both prelabor cesarean and labor induction are associated with late preterm birth.2 But it made me wonder how the overall changes compared to the United States.
The US has a higher preterm birth rate than South Australia (10% vs 7.1%); no single state in the US has a rate that low. There is also a large racial disparity in the United States which means for some groups the preterm birth rate is 14%. We have increased our preterm birth rate over time, though most recently we have been working to reduce it. We have also made improvements in preventing stillbirth, but this seems to have plateaued since the mid 2000s.3 So from a very quick glance, the relationship between preterm labor and stillbirth seems to be different in the United States than what is happening in South Australia.