In the 1960s, the use of the word miscarriage in Britain (instead of spontaneous abortion) came after changes in the law. Amniocentesis and chorionic villus sampling (CVS) are procedures used to assess the fetus. A sample of amniotic fluid is obtained by inserting a needle through the abdomen and into the uterus. Chorionic villus sampling is a similar procedure in which a tissue sample is taken instead of liquid. These procedures are not associated with pregnancy loss in the second trimester, but with miscarriages and birth defects in the first trimester.  Miscarriages due to invasive prenatal diagnosis (chorionic villus sampling (CVS) and amniocentesis) are rare (approximately 1%).  Medical providers often refer to miscarriages as spontaneous abortions or subcategories, including missed, incomplete, and unavoidable abortions (see Glossary). These terms are different from voluntary abortion, commonly referred to as abortion or „induced or therapeutic“ abortion in medical terms. Despite this, lawmakers have used „induced miscarriage“ or „miscarriage“ to describe deliberate attempts to terminate a pregnancy, illustrating how miscarriage and abortion can be easily mixed. For the avoidance of doubt, miscarriages and stillbirths refer to the spontaneous death of an embryo or fetus, but not to voluntary abortion.
What about legal substances? Some laws criminalizing the use of controlled substances during pregnancy do not distinguish between prescription and illegally purchased drugs. This makes women who are prescribed opioids for chronic pain or drug therapy (MAT) for opioid use disorders particularly vulnerable. For example, a woman in Alabama faced 20 years in prison and lost custody of her child after taking methadone prescribed during pregnancy.7 Meanwhile, a woman in Louisiana miscarried after receiving the contraceptive Depo-Provera from her doctor while she was unknowingly pregnant. She served more than a year in prison for second-degree murder before the charges were dropped. In 2016, Alabama signed an exemption for women who prescribed legally prescribed drugs from its Chemical Hazards Act. Yet a gray area remains over how the use of legal but non-prescribed substances — such as cigarettes, alcohol, herbal remedies and supplements — could be criminalized during pregnancy. An infected abortion can occur if, after a miscarriage, tissue from the placenta or fetus remains in the uterus. Symptoms of infection include fever, vaginal bleeding that does not stop, cramping and foul-smelling vaginal discharge. Infections can be serious and require immediate medical attention. In places where induced abortion is illegal or socially stigmatized, suspicion can surround miscarriage, complicating an already sensitive issue. Vitamin supplements have generally not been shown to be effective in preventing miscarriage.  Traditional Chinese medicine has not been found to prevent miscarriage.
 Miscarriages are extremely common, occurring in up to 30% of all pregnancies. However, pregnancy loss is often misunderstood and associated with induced abortions; For example, terms such as „induced miscarriage“ have been used to imply the intention to terminate the pregnancy, while „spontaneous abortion“ is a medical term for a miscarriage. This letter clarifies how pregnancy loss differs from abortion and highlights similarities in its management. It also focuses on how abortion policies can affect the treatment of miscarriages. At a time when abortion restrictions are increasing across the country, laws can limit providers` ability to manage pregnancy loss and women who suffer from pregnancy loss can be screened to prove their miscarriages were unintentional. This letter explores how measures to restrict abortion can have a negative impact on people with pregnancy loss. Miscarriage occurs in all animals that experience pregnancy, although in such contexts it is more often referred to as spontaneous abortion (the two terms are synonymous). There are a variety of known risk factors in non-human animals. For example, in sheep, miscarriage can be caused by pushing doors or being chased by dogs.
 In cows, spontaneous abortion can be caused by infectious diseases such as brucellosis or Campylobacter, but can often be controlled by vaccination.  Many shark and ray species often experience stress-related miscarriages when captured.  Recurrent pregnancy loss (RPL) or habitual abortion is the occurrence of multiple consecutive miscarriages; The exact number used to diagnose recurrent miscarriages varies.  If the proportion of pregnancies ending in miscarriage is 15% and miscarriages are assumed to be independent events, then the probability of two consecutive miscarriages is 2.25% and the probability of three consecutive miscarriages is 0.34%.