What could cause a miscarriage

Posted on 23 August 2016

Just found out you’re expecting, or planning a pregnancy? The fear of a miscarriage is very real for most prospective parents. Dr Jackson Ndhlovu, a gynaecologist at Mediclinic Tzaneen, talks us through what could cause a miscarriage and what you can do to ensure a healthy pregnancy.

What is a miscarriage?
Miscarriage is a failed intrauterine pregnancy that results in the death of the foetus in the womb before the 20-24th week of pregnancy, after which foetal death is called a stillbirth, Dr Ndhlovu explains.

Studies show that 8-20% of women who know they are pregnant have a miscarriage sometime before 20 weeks of gestation, and 80% occur in the first 12 weeks of pregnancy – the first trimester. Actual figures are probably much higher, because many women have an early miscarriage without even knowing that they are pregnant. Second-trimester miscarriages, between 13 and 19 weeks, occur in just 1-5% of pregnancies.

It’s also important to note that miscarriages are clinically defined as complete, incomplete, inevitable, threatened or induced.

What causes miscarriage?
It is difficult to say with certainty what causes a particular miscarriage to occur, says Dr Ndhlovu, but there are certain identifiable risk factors associated with first trimester miscarriages:

•    Maternal age: Women over the age of 35 are more likely to have a miscarriage.
•    Chromosomes: Chromosomal abnormalities account for the majority of miscarriages.
•    Previous miscarriages: Women with a history of miscarriage have an increased risk in subsequent pregnancies.
•    Autoimmune diseases: The biggest risks are for women who suffer from lupus or antiphospholid syndrome (APL), in which immune cells attack the phospholipids found in the walls of the placenta.
•    Uterine abnormalities: These include the presence of fibroids in the endometrium (the mucous membrane that lines the inside of the uterus), or an abnormally shaped uterus.
•    Lifestyle factors: Smoking and obesity increase your risk of miscarriage, and no amount alcohol is known to be safe during pregnancy.
•    Fever: Developing a temperature of 38°C or higher while pregnant is a risk factor.
•    Trauma: Trauma to the uterus caused by blunt force or prenatal testing such as amniocentesis or chorionic villus sampling (a test sometimes done in early pregnancy) can increase the risk of miscarriage.
•    Other predisposing factors: These include certain infections, medications, radiation, physical stress and environmental chemicals.
•    Caffeine: By itself caffeine does not appear to cause miscarriage, but a high intake – 1 000mg, or 10 cups of coffee, over a period of 8 to 10 hours – can be risky.

In the second trimester your chances of a miscarriage fall dramatically, but Dr Ndhlovu lists these possible risk factors:
•    Uterine complications: These include cervical incompetence, when the cervix is weakened and begins to dilate too early in pregnancy; and submucosal fibroids, that distort the shape of the womb and thin its lining.
•    Poor blood supply to the foetus: This can be caused by hypertension, poorly controlled diabetes, autoimmune diseases, or placental insufficiency.

What can moms-to-be do to ensure a healthy pregnancy?
Dr Ndhlovu stresses the importance of a pre-pregnancy consultation with a doctor or clinic nurse for advice and education about diet, lifestyle, and family planning, especially if you are on medication or have a chronic medical condition.

He recommends using this checklist in your pre-pregnancy consultation:
•    Mention any medication you are taking: For example medication for conditions such as epilepsy, diabetes, hypertension, TB, HIV, lupus and so on. Also list any herbal remedies and/or supplements.
•    Check if you are up to date with your vaccines: This includes MMR (mumps, measles, rubella), tetanus, hepatitis, etc. Most vaccines cannot be given during pregnancy.
•    Share your family history of hereditary conditions: If anyone in your or your husband’s immediate family has cystic fibrosis, muscular dystrophy, mental or physical birth handicaps, and so on, you should inform your nurse or GP.
•    Underlying medical conditions: If you have a cardiac, lung or thyroid condition or suffer seizures, or have miscarried before, your nurse or GP should explain to you the risks of pregnancy for both mother and fetus.

Dr Ndhlovu also recommends that you follow a healthy lifestyle before and during pregnancy. Here are his top tips:
• Stop smoking – and encourage your partner to do the same.
• Don’t drink alcohol or use drugs.
• Maintain a healthy weight.
• Start taking folic acid. This reduces the risk of neural tube defects, and ideally you should start taking it three months before pregnancy.
• Be careful what you eat. Avoid raw or undercooked meat and fish, and raw shellfish such as oysters. Don’t eat fish with high levels of mercury, such as swordfish and king mackerel. Don’t drink unpasteurised milk, limit your caffeine intake and be sure to wash raw fruits and vegetables before eating.

If you’ve had a miscarriage, how soon can one try to get pregnant again?
There are no definitive guidelines, but it is preferable to wait until your menstruation cycle is back to normal, says Dr Ndhlovu. Consult your GP or clinic nurse for advice on contraception choices during this time.

He adds that many women ask when it is safe to resume sex after a miscarriage. This is also a grey area, but the simple answer is whenever the woman feels physically and emotionally ready. Dr Ndhlovu also stresses that it’s important for couples to address any emotional issues they may have after a miscarriage before planning their next pregnancy. Once you feel ready to try again, make sure to consult your GP or nurse with the checklist outlined above.

Additional sources: webmd.com, thebump.com

Published in Pregnancy

In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.

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