The overall rate of stillbirths in British Columbia increased by 31% from 2000 to 2010. This temporal trend was due to increases in pregnancy terminations. The rate of spontaneous stillbirths with a birth weight of 1000 g or more declined significantly, whereas rates of spontaneous stillbirth at 28 weeks’ gestation or later showed a nonsignificant decline. The observed increase in stillbirths due to pregnancy termination was accompanied by a simultaneous decrease in the prevalence of congenital anomalies among live-born infants. This concurrence suggests that advances in, and increased uptake of, prenatal diagnosis are having a population-level impact on the timing of death and the gestational age at delivery of fetuses with congenital anomalies.
Stillbirths following termination of pregnancy constituted 26% of fetal deaths in New Zealand in 2009.7
Stillbirths in the United Kingdom in 2009 included a smaller proportion of pregnancy terminations because pregnancy terminations were excluded from stillbirth calculations in England and Wales (but not Scotland).8
Not surprisingly, the proportion of stillbirths with a major anomaly as the primary cause of death varied between these regions: 8.0% in England, 5.7% in Wales and 15.6% in Scotland.8
Differences in the definition of stillbirth affect the frequency with which pregnancy terminations are included among stillbirths. Most pregnancy terminations in our study occurred between 20 and 23 weeks’ gestation, whereas some countries (e.g., the UK) consider fetal deaths to be stillbirths only if they occur at 24 weeks’ gestation or later. Such variations in definitions and birth registration practices are responsible for changes in the ranking of countries based on crude stillbirth rates versus ranking based on rates of stillbirths with a birth weight of 1000 g or more.16–19
Concerns regarding maternal and fetal health status are not misplaced given recent increases in the frequency of risk factors for adverse perinatal outcomes, including higher maternal age, weight before pregnancy and multiple births.11–13
However, we found that adjustment for such changes did not substantially accentuate the declining trends in spontaneous stillbirth in our study (). Recent developments that have enhanced maternal and fetal health include reductions in maternal smoking,1,20
fortification of food with folic acid,21,22
therapies for pre-eclampsia23
and improvements in fetal growth.1,20
Prenatal diagnosis has also shifted the burden of illness associated with congenital anomalies. Infant deaths and late fetal deaths due to serious congenital anomalies are increasingly being replaced by pregnancy terminations before 24 weeks’ gestation following prenatal diagnosis.24,25
Although our study showed that the increase in stillbirths due to pregnancy termination (presumably after prenatal diagnosis) occurred simultaneously with a reduction in the prevalence of congenital anomalies among live-born infants, other factors may have also contributed to the latter change. For instance, fortification of food with folic acid, introduced in Canada in 1998, may have contributed to declines in the prevalence of congenital anomalies.21,22
In addition, increases in maternal age may have contributed to increases in the prevalence of Down syndrome among live-born infants.1
Surveillance for preventable stillbirth remains an important public health function and requires that a distinction be made between stillbirths that occur spontaneously and those that follow pregnancy termination for serious congenital anomalies or other reasons. The processes associated with stillbirth registration following pregnancy termination can also cause unintended psychosocial harm to women and their families. For instance, in many jurisdictions, parental involvement is required in the stillbirth registration process (similar to live birth registration), which often places an undue psychological burden on parents. The situation can be exacerbated when the stillbirth registration occurs some time after the fetal death, as in case of fetal reduction for multifetal pregnancy (e.g., reduction of a triplet pregnancy to a twin pregnancy at 10–14 weeks’ gestation, delivery of twins and the dead fetus at term, and the need for stillbirth registration because the dead fetus was delivered after 20 weeks’ gestation). One solution to this procedural problem would have the onus for stillbirth registration (and disposal of the fetal remains) placed on the health care provider and health care system and not on the distressed parents.
Strengths and limitations
Our study was based on a population registry of live births and stillbirths and included both hospital and home births. The registry is comprehensive, and the primary findings of our study are unlikely to have been compromised by missing live births or stillbirths. Nevertheless, some secondary analyses in our study were affected by missing data, especially missing information on birth weight. However, the temporal increase in the rate of stillbirths with missing birth-weight data probably occurred because pregnancy termination procedures can interfere with the accurate estimation of birth weight (but not gestational age, as shown in ). Other limitations of our study include potential inaccuracies and missing information on self-reported maternal weight before pregnancy.
Increases in pregnancy terminations were responsible for the increases observed in stillbirth rates from 2000 to 2010 and were associated with declines in the prevalence of congenital anomalies among live-born infants. Future research examining temporal trends and regional variations in stillbirth rates should focus separately on spontaneous stillbirths and those due to pregnancy termination.