Within the medical literature, pregnancy loss is divided into miscarriage, a loss occurring before 20 weeks gestation, or fetal demise (often called stillbirth), which is a loss occurring after 20 weeks gestation. The distinction is based on our current understanding of viability, or the ability to survive outside the womb. With current medical practices, a child born before 20 weeks gestation has a very small chance of survival where a child born after 20 weeks gestation often survives with the prognosis improving the longer the child stays within the womb. Although there is some overlap, there are different reasons one might have a miscarriage compared to a fetal demise.
When a woman has a miscarriage, we often don’t know its cause but most are assumed to be from chromosomal abnormalities. Although some chromosomal abnormalities are compatible with life (for instance trisomy 21 which is the most common type of Down Syndrome), most chromosomal abnormalities are not. Age is a risk factor for a miscarriage due to chromosomal abnormalities with women over the age of 35 carrying the greatest risk. Other causes include abnormalities of the uterus such as polyps or abnormal uterine shape; hormonal abnormalities such as a low level of progesterone that would normally stabilize the pregnancy; medical conditions such as thyroid disorders or diabetes; lifestyle choices including malnutrition, drugs, alcohol, stress, or smoking; clotting disorders where the blood clots too easily; or diseases where the immune system can be over active which we see in endometriosis or lupus.
The causes of fetal demise (a pregnancy loss after 20 weeks gestation) are also varied. Some of the medical conditions (diabetes and untreated thyroid disorders) that lead to miscarriage can also lead to a loss later in the pregnancy. This is also true of some of the immunological disorders, clotting disorders and lifestyle choices. Additionally, some children with birth defects or chromosomal abnormalities might survive the early pregnancy but have more stress as they grow which can lead to a fetal demise rather than a miscarriage.
Causes more unique to fetal demise consist of Infections, including some infections caused by sexually transmitted infections (STIs); umbilical cord accidents (prolapse, torsion, entanglement) that kink the cord or in some other way prevent oxygen from getting to the baby; inadequate placenta health which can result from diabetes, a post dates pregnancy or a placental abruption where the placenta loses its attachment to the uterine wall; high blood pressure diseases of pregnancy such as preeclampsia and eclampsia; or pregnancy loss due to a failure to address blood type incompatibilities such as Rh factor or ABO incompatibility.
With the many possible reasons for a pregnancy loss, there are varied treatments as well. For information regarding the treatment of miscarriages and fetal demise and for prevention of miscarriages, please see Treatment Options. If you have a non-emergent, general question about pregnancy loss, please email info@teachmehealme.com. Although our physicians would love to assist everyone, we are unable to provide specific treatment recommendations to patients not under our care. So please remember to discuss any questions or concerns with your primary health provider as well.
