Definitions, Epidemiology, and Risk Factors
This chapter addresses the management of stillbirth, defined as a fetal death occurring with these other criteria.
Occurring at 20 weeks or greater
OR
350g or more if EGA is unknown
This placental complication is considered causal when clinical signs of a large event are present, or histopathology involves >=75% of the placenta
Placental abruption
This single examination is described as the most useful aspect of the stillbirth evaluation
Pathological evaluation of the placenta, umbilical cord, and fetal membranes (64.6% of cases).
Fetal autopsy is second (42.4%)
Between 80% and 90% of patients will enter spontaneous labor within this time period following fetal death.
2 weeks
In case-control studies, women with stillbirth are reported to have a several fold increase in this symptom when compared to women with live births.
Decreased fetal movement
According to the chapter, in the United states, stillbirth occurs in this many pregnancies.
1 in 165 / 5.7 in 1000
Parvovirus B19 causes stillbirth through this mechanism
Destruction of fetal hematopoietic tissue --> anemia --> hydrops
Unlike antiphospholipid antibody syndrome, testing for these is NOT recommended as part of a stillbirth evaluation.
Inherited thrombophilias
Before 28 weeks gestation, this medication is the most efficient method of labor induction for stillbirth regardless of Bishop score
Misoprostol
Even in the setting of a prior LTCS
Improved antenatal detection of this obstetric condition is one of the most promising strategies for the detection of stillbirth risk.
Fetal Growth Restriction
In 2019, the US stillbirth rate was 5.7 per 1000 births. Non-Hispanic Black women experience a rate that is this many times higher than non-Hispanic White women.
2.2x
B: 10.4 per 1000
W: 4.71 per 1000
H: 4.79 per 1000
The presence of this maternal factor, in combination with maternal diabetes, has a synergistic effect on the rate of stillbirth.
Obesity
The combination is stronger than the combined individual effects
This maternal study should be considered in cases where stillbirth is associated with PPROM, PTL, and cervical insufficiency, especially if the demise occurs near periviability or intrapartum.
Assessment of the uterine cavity
In subsequent pregnancies after stillbirth, antepartum fetal surveillance is recommended to begin at this gestational age
32 weeks
OR
1-2 weeks prior to the gestational age of the prior loss
In at risk women, low dose aspirin is associated with a decrease in the rate of fetal or neonatal death with a number needed to treat of 243, or a reduction by this percent.
14% reduction in fetal and neonatal death
There is a J-shaped relationship between the risk of stillbirth and this maternal factor.
15-19 and 45+ have nearly 2x the rate of stillbirth as those aged 30-34yo.
In the SCRN, vascular degenerative changes in the chorionic plate were found in 55.7% of stillbirths but only 0.5% of livebirths. Loss of more than this percentage of fetal blood volume (in mL/kg) has been associated with a 26% stillbirth rate.
25% of fetal blood volume (>=20mL/kg)
This maternal serological study is most reliable when performed prior to the onset of labor.
Fetal to maternal hemorrhage testing by Kleihauer-Betke or flow cytometry
Labor and delivery may result in false positives
For women with a previous low-transverse uterine incision and a uterus greater than 28 weeks size at the time of stillbirth, this combination of induction agents and cervical ripening method is recommended
Oxytocin and foley balloon
Decreased impedance of flow in the uterine arteries manifests an abnormal Doppler waveform. This finding is associated with placenta related stillbirth due the failure of this physiologic process early in pregnancy.
Failure of trophoblastic invasion of the spiral arteries
In the SCRN multivariate analysis, this pregnancy history group had the highest adjusted odds ratio for stillbirth (5.91; 95% CI 3.18-11.00) when compared to multiparous women with no prior pregnancy loss.
Multiparous women with a history of stillbirth
Having a history of prior livebirth was somewhat protective
History of SGA in a prior pregnancy is also high risk (aOR 5.0 - 5.6)
Confined placental mosaisicm is associated with increased risks of adverse perinatal outcomes including FGR, EPL, and stillbirth. This specific chromosomal finding is associated with a high probability of fetal death.
Confined placental mosaicism with trisomy 16
High risk of stillbirth, PTB, FGR, and anomalies
Less than 1/3 will deliver a full term, normally grown infant.
This testing method is considered the first line for genetic diagnosis in the evaluation of stillbirth.
Chromosomal microarray
Yields results more often
Detects small CNVs (50kb)
Works with non-viable tissue
Coagulation abnormalities occur in 3-4% of patients with uncomplicated fetal deaths after 4-8 weeks, caused by the gradual release of this substance by the decidua or placenta
Tissue factor
Initiates the extrinsic pathway of the coagulation cascade.
Abnormalities in these two biochemical markers have a synergistic effect on the risk of stillbirth. When both are abnormal, the OR for stillbirth is 36.7.
PAPP-A < 5th percentile (OR 2.2)
MSAFP > 2.5 MoM (OR 2.5)