DEFINITION & INCIDENCE
Stillbirth is a term used to define fetal death or fetal demise later on in pregnancy, starting at >20 weeks of gestation, according to the United States National Center for Health Statistics. Stillbirth differs from miscarriage in that the latter refers to pregnancy loss at <20 weeks of gestation. In the United States, stillbirth occurs in about 1 out of every 160 pregnancies, that is approximately 26,000 stillbirths per year.
CAUSES
Stillbirth is the end result of various maternal, fetal and placental conditions. The most common causes include obstetrical complications, placental disorders, fetal chromosomal/genetic defects, maternal or fetal infections, hypertensive states, and umbilical cord abnormalities. Unfortunately, stillbirth cannot be attributed to one of the identifiable etiologies at times, and is considered unexplained.
Since my loss was believed to be the outcome of umbilical cord accident (UCA) or compression, I was consumed by it and was very determined to learn everything there is to know about it, which sadly, is not much. Umbilical cord accidents represent 10% of stillbirths. A normal cord has a single vein and 2 arteries that have a twisted rope-like appearance. Lack of twisting is frequently linked to a reduction in fetal movement and poor pregnancy outcome.
Nuchal cord refers to an umbilical cord that wraps around the fetal neck in a full 360 degree fashion.
According to Collins (2012):
"Hyperactivity is a fetal response associated with umbilical cord compression risk factors. This fetal behavior may be related to intrauterine umbilical blood flow disturbance, which stimulate the fetus to react reflexively and excessively. Hyperactivity may be a prenatal behavior capable of repositioning the fetus and relieving the compression."
Did I feel those erratic kicks or the so-called "hyperactivity" because my baby was in distress and trying to free herself?
In animal studies (rats), simulation of umbilical cord compression produced "lateral trunk curls, head tosses and foreleg extensions". In sheep studies, sporadic umbilical cord compression prompted fetal hiccups. Continuous daily hiccups after 28 weeks and greater than 4 occurrences/day should be reported to the care provider for further fetal evaluation.
Per findings from large retrospective studies, there is no evidence to suggest that there is an increased risk of stillbirth in fetsuses with nuchal cords in comparison to those without. Nonetheless, despite normal pre/post natal assessment, there have been case reports of stillbirths in the setting of one or more nuchal cords, presence of indentation marks around the fetal neck and lack of other explicable causes for the demise, which suggests that nuchal cords can seldom be the cause of fetal loss.
One possible explanation for fetal suffocation is the restriction of blood flow in one of the major arteries in the neck, the carotid artery, due to tight entanglement around the neck, although severe venous congestion (overfilling and distention of veins with blood due to the mechanical obstruction), may be enough to result in asphyxia and death. Another conceivable explanation is the compression of the arteries and vein of the umbilial cord as the cord tightens against itself or the neck of the fetus.
A study by Stillbirth Collaborative Research Network, was designed to determine the cause of death among stillborn babies. Nuchal cords have been reportedly observed in approximately 25% of normal pregnancies. Inclusion for a cord related abnormality as the cause of fetal demise in this study was per Bukowski, et al. (2011),
"rigorous and included vasa previa, cord entrapment, and evidence of occlusion and fetal hypoxia, prolapse, or stricture with thrombi. Nuchal cord alone was not considered a cause of death."
The last statement is highlighted to emphasize the rarity of nuchal cord related deaths, or the lack of understanding and evidence that some cord conditions may be related to a physiological process that leads to stillbirth, which is why cord abnormalities necessitate further scrutiny.
RISK FACTORS
- Chronic or pregnancy induced hypertension (high blood pressure)
- Diabetes
- Systemic lupus erythematosus
- Kidney disease
- Thyroid disorders
- Smoking or illicit drug use
- Obesity
- Previous growth resricted infant
- Previous cesarean section
- Previous stillbirth
- Multiple gestation (twins or triplets)
- Maternal age (>35)
- Race and socioeconomic factors
STRATEGIES FOR PREVENTION OF STILLBIRTH
Per a systemiac review, close observation and appropriate treatment of the following conditions has decreased the incidence of stillbirth worldwide
- Folic acid consumption before conception
- Malaria prevention
- Syphilis detection and treatment
- Treatment of hypertension and diabetes
- Detection of fetal growth restriction and management
- Recongition of postterm pregnancy (>41 weeks) and planned induction
- Fetal monitoring in the late second or third trimester may identify fetuses in whom timely intervention will prevent death.
PREVENTION OF RECURRENT STILLBIRTH
- Fetal surveillance - according to American College of Obstetrician and Gynecologists, in otherwise healthy women with prior stillbirth, fetal testing should begin 1-2 weeks prior to the gestation age of the previous stillborn baby and by 32 to 34 weeks
- Timing delivery - to provide psychological reassurance, some clinicians deliver babies before the estimated due date. Amniocentesis is recommended before any elective delivery < 39 weeks and fetal lung maturity should be confirmed before a scheduled delivery.
REFERENCES:
- Frett, R. C. (Feb 2016). Fetal demise and stillbirth: incidence, etiology, and prevention. In C. J. Lockwood (Ed.), UpToDate. Waltham, Mass.: UpToDate. Retrieved from https://www-uptodate-com.ezproxy.med.nyu.edu/contents/fetal-demise-and-stillbirth-incidence-etiology-and-prevention?source=search_result&search=stillbirth&selectedTitle=1%7E150
- Collins, J. H. (2012). Umbilical cord accidents. BMC Pregnancy and Childbirth, 12(Suppl 1), A7. http://doi.org/10.1186/1471-2393-12-S1-A7
- Causes of Death Among Stillbirths. JAMA. 2011;306(22):2459-2468. doi:10.1001/jama.2011.1823.
- Schaffer, L. and Zimmermann, R. (May 2016). Nuchal cord. In S. Ramin (Ed.), UpToDate. Waltham, Mass.: UpToDate. Retrieved from https://www-uptodate-com.ezproxy.med.nyu.edu/contents/nuchal-cord source=search_result&search=nuchal +cord& selectedTitle=1%7E13