What week is the highest risk of a miscarriage?
The first trimester is associated with the highest risk for miscarriage.
Most miscarriages occur in the first trimester before the 12th week of pregnancy. A miscarriage in the second trimester (between 13 and 19 weeks) happens in 1% to 5% of pregnancies.
Early pregnancy loss is defined as a nonviable intrauterine pregnancy with either an empty gestational sac or a gestational sac containing an embryo or a fetus without fetal heart activity within the first six to seven weeks of pregnancy. This means that a miscarriage may occur if pregnancy fails to progress due to either an empty gestational sac or a lack of fetal heart activity in an embryo. The incidence of a miscarriage in the first six weeks is as high as 31%.
The risk of a miscarriage decreases by 10% after the pregnancy crosses six weeks. Once the fetal heart activity is established after six weeks, there is a decreased chance of failed pregnancy.
Early second-trimester pregnancy loss or late miscarriages occur after 13 and before 20 weeks of pregnancy. The incidence of second-trimester pregnancy loss is less than 1%.
Stillbirth or fetal death: Pregnancy loss that occurs at or after 20 weeks of pregnancy or at a weight of 350 grams (about ¾ of a pound) or greater is generally referred to as a stillbirth or fetal death. The approximate rate of stillbirth in the United States is 6 per 1,000 live births and stillbirths.
What is a miscarriage?
Miscarriage, also known as spontaneous abortion, is a spontaneous loss of pregnancy before the 20th week. Half of pregnancies may end in a miscarriage. Women who experience miscarriages may subsequently have a healthy pregnancy later.
What causes a miscarriage?
Chromosomal abnormalities are one of the major causes of a miscarriage. Other causes include
- Maternal age
- Uterine abnormalities
- Hormonal irregularities
- Infections such as herpes, syphilis or listeriosis
- Incompetent cervix (cervix dilates too early during pregnancy without pain or contractions)
- Improper implantation of the fertilized egg in the uterine lining
- Blighted ovum (embryo implants in the uterus but doesn’t develop into a baby)
- Intrauterine fetal demise (embryo stops developing and dies)
- Molar pregnancy (tissue in the uterus forms into a tumor)
- Translocation (when part of a chromosome moves to another chromosome)
- Septate uterus (band of muscle called septum divides the uterus into two sections)
- Asherman syndrome (scars in the uterus that can damage the lining of the uterus)
Who is at a risk for a miscarriage?
Factors that may increase the risk of a miscarriage include
- History of two or more previous miscarriages
- Over the age of 35 years old
- Smoking
- Drinking alcohol
- Drug abuse
- Being exposed to harmful chemicals
- Autoimmune disorders such as systemic lupus erythematosus
- Obesity
- Hormonal problems such as polycystic ovarian syndrome (PCOS)
- Preexisting diabetes
- Thyroid problems
- Prenatal tests such as amniocentesis or chorionic villus sampling
- Caffeine consumption
- Congenital heart disease
- Severe kidney disease
- Severe malnutrition
- Radiation
- Certain medications such as Accutane (isotretinoin)
What are the signs and symptoms of a miscarriage?
Signs and symptoms of a miscarriage include
- Bleeding from the vagina or spotting
- Period-like cramps
- Severe abdominal pain
- Low backache ranging from mild to severe
Call the physician if you observe these symptoms of infection after a miscarriage