A quarter of stillbirths are preventable by increased obstetric surveillance

Placental insufficiency was identified as the lead cause of potentially preventable stillbirths, followed by medical complications of pregnancy and hypertensive disorders of pregnancy, reported the result of a small study conducted by Jessica M. Page, MD, of the University of Utah School of Medicine, and her colleagues. 

The stillbirth rate in the US was 5.96 per 1,000 births in 2013 and has remained stable since the last decade. Although it is much lower than the global rate of 18.4/1,000 births, it is higher than rates in other developed countries.

Currently, Finland has the lowest stillbirth rate of 2 per 1,000 births, while Pakistan has the highest rate of 43.1 per 1,000 births. Other countries with relatively low stillbirth rates included Norway, Denmark, and Singapore. 

The researchers conducted a secondary analysis of 512 stillbirths from the Stillbirth Collaborative Research Network with post-mortem data and placental histopathology. They identified 114 (22.3%) that were potentially preventable; 27 of those were included in more than one category, of which 23 fit into two categories and 4 fits into three categories.

In fact, one-third of stillbirths due to placental insufficiency had another cause identified as well. When the stillbirths due to placental insufficiency were analyzed further, it was seen that they increased with increasing gestational age, the most common window being after 37 weeks of gestation. The stillbirths due to other causes (potentially preventable and nonpreventable) did not increase with increasing gestational age.

But, the researchers did notice a significant increase in the proportion of potentially preventable stillbirths with increasing gestational age (P=.023). Notably, 39 out of 114 preventable stillbirths occurred after 37 weeks of gestation, when the risk of prematurity was at its minimal, had they been detected at risk of intrauterine death (IUD) and delivered.

When the researchers looked at the role played by race and ethnicity, they did not find any significant difference between various cohorts.

The majority of stillbirths in low resource setting can be preventable, while there is no clue regarding how to bring down the stillbirth rate in developed countries. There are few risk factors that increase the risk of stillbirths like smoking, obesity, advanced maternal age, and multiple gestations but it is not known that how far the risk can be lowered by modification of these factors.

Researchers are optimistic to get some clue regarding prediction of third-trimester stillbirths from data obtained from the Eunice Kennedy Shriver National Institute of Child Health and Human Development–sponsored Human Placenta Project.

The study has many limitations, but it also did include a large number of well-characterized stillbirths from racially, ethnic and geographically diverse population.

This study underscores the importance of close obstetric surveillance with nearly 25% of stillbirths deemed potentially preventable.

The study was published in February 2018 issue of Journal of Obstetrics and Gynecology and also presented as a poster at the Society for Maternal-Fetal Medicine’s 36th Annual Pregnancy Meeting, February 1–6, 2016, Atlanta, Georgia.

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Trying to Understand Stillbirths

Stillbirths affects 1% of all pregnancies in US, amounting to nearly 24,000 deaths every year. Recent advances in medicine has brought down the neonatal and infant mortality considerably in last decade, but the decline is still birth rate is very slow.

A lack of understanding of the mechanisms behind it coupled with inability to predict stillbirth has prevented significant improvement in stillbirths’ rate.

Although altered fetal growth and placental abnormalities are strongest predictors of stillbirths but all patients with placental abnormalities do not end up in stillbirths, reflecting our lack of understanding of this interrelationship.

This population based case control study included 613 women who had stillbirths and 1747 women who had live births and who consented to placental pathological examination from 59 hospitals in 5 geographic areas in the U.S.

Study was published online August 18, 2017 in Journal PloS one.

About 15 placental pathologies were most prevalent in women with stillbirths and fetal growth abnormalities.

Out of 15, ten were also associated with fetal growth retardations. These are: single umbilical artery; velamentous insertion; terminal villous immaturity; retroplacental hematoma; parenchymal infarction; intraparenchymal thrombus; avascular villi; placental edema; placental weight; ratio birth weight/placental weight)

The other 5 (acute chorioamnionitis of placental membranes; acute chorioamionitis of chorionic plate; chorionic plate vascular degenerative changes; perivillous, intervillous fibrin, fibrinoid deposition; fetal vascular thrombi in the chorionic plate) resulted in stillbirths without altered fetal growth.  

Terminal villous hypoplasia was equally common in live born and still born fetuses with altered fetal growth.

Maternal factors associated with still births were gestational hypertension/pre-eclampsia (20% versus 11%, p<0.001), hypertension before pregnancy (11% versus 5%, p<0.001), and pregestational diabetes (7% versus 2%, p<0.001)

Fetal factors associated with still births were congenital malformations (13% versus 3%, p<0.001), lower birth weight (median 1,949 versus 3,321 grams, p<0.001), and lower GA (median 33 versus 39 weeks, p<0.001).

The study results suggest that different mechanisms exist for disruption in placental function and the results vary according to timing of gestation. An acute insult results in still births but no fetal growth alterations while a chronic, low level insult results in fetal growth retardation which may end up in still births.

Some of these placental findings can be diagnosed with prenatal ultrasound and pregnancies managed accordingly, Similarly, birth weight to placental weight ratio could be estimated antenatally by ultrasound and those pregnancies with abnormal ratio and at risk of stillbirths could benefit from early  term delivery.

Access the abstract, Full Text.