Having a pregnancy loss can be heartbreaking. Having multiple miscarriages can be truly devastating. Each new pregnancy brings hope, but also great anxiety; each new miscarriage aggravates the feelings of loss, grief and sense of failure… 

It is natural to want answers. Knowing the reason of a pregnancy loss can help you make sense of what has happened. Furthermore, finding the cause of the problem will help prevent it from happening again, or at least reduce its risk. Things are not so simple though when it comes to recurrent miscarriage: most of the times, investigations don’t come out with a clear answer…

The purpose of this article is to help you understand recurrent pregnancy loss and to present the most recent scientific information regarding its cause, diagnosis and treatment. Due to the extensiveness of the subject, this first article will deal only with the known causes of repeated miscarriage; two other articles on testing and treatment will follow.

What is Recurrent Pregnancy Loss?

A pregnancy loss is the spontaneous loss of a pregnancy before 24 weeks of gestation. Recurrent Pregnancy Loss (RPL) is considered after the loss of two or more pregnancies; this includes pregnancies after spontaneous conception or after assisted reproduction (e.g. IUI and IVF/ICSI). Other pregnancy complications such as ectopic pregnancies and molar pregnancies are not included. 

  • Primary RPL is a term used for women who have not had a baby before their pregnancy losses. 
  • Secondary RPL means they have had at least one baby before their losses. 

It is estimated that RPL affects 1 to 2% of couples.

What causes RPL?

There are several factors that may be responsible for RPL. But you should know that in about half (50%) of the RPL cases, no cause is found. This is called unexplained RPL.

Here are some of the causes that are related to multiple miscarriages:

1) Age

The older you are, the greater your risk of having a miscarriage. If a woman is aged over 40, more than 50% of pregnancies end in a miscarriage. The same is true for RPL. Miscarriages may also be more common if the father is older, although it is not clear whether paternal age is related to repeated miscarriages.

2) Genetic problems

  • Genetic defects resulting in an abnormal fetus can be a major cause of miscarriage. About half of all miscarriages in the first three months of pregnancy are due to chromosomal problems, although most of the times this is of random occurrence .
  • In about 4 in 100 couples (4%) with recurrent miscarriage, one partner will have an abnormality on one of their chromosomes. Although this may not affect the parent, it may sometimes cause a miscarriage.

3) Thrombophilia

Thrombophilia is a condition in which your blood clots more than usual; it may be inherited (passed down genetically) or acquired (not inherited). Thrombophilia is not only related to RPL, but also to other pregnancy complications.

  • Inherited thrombophilia is due to certain gene defects. According to the gene involved, it may be related to early or late repeated miscarriage.
  • Antiphospholipid syndrome (APS) is an acquired thrombophilic condition. It is uncommon but strongly related to RPL.

4) Abnormal hormone levels

Miscarriage can occur when the uterine lining does not develop sufficiently, therefore the fertilized egg does not have the best environment for implantation and nourishment; this can be the result of abnormal hormone levels.

Women with thyroid problems and women with diabetes (or insulin problems) are usually at a higher risk for miscarriage due to hormonal imbalances. Women with polycystic ovaries syndrome, are also at risk. In addition, elevated prolactin levels can also disrupt normal uterine lining development.

5) Problems of the uterus

The shape of the uterus may cause miscarriage, usually by interfering with the implantation of the fertilized egg.

  • A septum, that is a fibrous wall which divides the uterine cavity, can cause poor implantation and pregnancy loss.
  • Uterine fibroids, polyps, adhesions may eventually cause pregnancy loss by blocking the opening of the fallopian tube(s) or if their position is affecting the normal functioning of the uterine lining. Their relationship though with RPL is less clear.
  • Another probable cause of miscarriage is an incompetent cervix, meaning the cervical muscle is weak and cannot remain closed; as the developing fetus grows puts pressure on the cervix, it starts to shorten and open, resulting in miscarriage.

6) Immune Causes

It has been suggested that some women miscarry because their immune system does not respond to the baby in the usual way. This is known as an alloimmune reaction. Although numerous immunological factor have been investigated, there is no clear evidence to support this theory at present, and further research is needed.

7) Sperm defects

Sperm DNA is the most important part of the sperm, as it contains the genetic information that will be passed on to the baby. DNA can be damaged during sperm production and transport; this damage is known as DNA fragmentation. The recents years it has become evident that high levels of sperm DNA fragmentation seem to increase the likelihood of pregnancy loss.

Sperm DNA fragmentation can be provoked by stress, smoking, recreational drugs, obesity and other unhealthy lifestyle factors. 

8) Infections

Certain infections have been proposed as the cause of RPL, such as rubella, herpes simplex, ureaplasma, cytomegalovirus and chlamydia. However, the role of these infections in recurrent miscarriage is unclear and probably null. A persistent infection of the endometrium (chronic endometritis) may be related to RPL, but more research is needed to know this for sure.

9) Environmental Factors

Certain toxins you may be exposed to can also result in fetal damage or miscarriage, especially if you experience regular exposure. Toxins such as organochlorine pesticides, certain heavy metals (selenium, lead cadmium), organic solvents, anesthetic gases (occupational exposure), have all been blamed for causing RPL. Likewise, lack of certain micronutrients (zinc, copper, vitamin E) have been proposed as possible causes of RPL. 

Although exposure to possible hazardous substances should be avoided during pregnancy (this is true for all pregnant women), there are insufficient data to recommend protection against a certain occupational or environmental factor in women with RPL.

10) Lifestyle-related factors 

  • Studies also indicate that the use of marijuana, tobacco, alcohol and excessive consumption of caffeine can all affect fetal development and result in miscarriage. Although their relationship with RPL is not clear, it is recommended that women limit or avoid their use during pregnancy.
  • Being overweight or significantly underweight have been both associated with miscarriages, as well as with pregnancy and childbirth complications. While maternal obesity is a strong risk factor in RPL, the association with very low weight is less clear. Male overweight may also be a negative factor, since is responsible for DNA damage (see above). Striving for a healthy, normal weight is recommended, both for the female and male partner. 
  • Intensive exercise or no exercise at all have been both blamed as a cause of RPL, but there is not clear scientific evidence and further research is needed. Moderate (leisure) physical activity seems to be safe, and beneficial for other pregnancy complications, such as diabetes and hypertension of pregnancy.
  • Whether stress increases the chances of another pregnancy loss in the next pregnancy is a major concern for all couples with RPL. Studies to date indicate that there is an association between stress and pregnancy loss, but it is not whether the stress is a result or a causal factor in RPL.


Read the second part here: Understanding Recurrent Pregnancy Loss – Testing (coming soon)


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Yes!! the pregnancy test is positive! You go and share the good news with your friends and relatives…And that very same moment, people will start “bombarding” you with advices: do this, don’t do that… So you start wondering: What is safe? What can harm my baby?

This post is about the most common “Is it safe….?” questions. Since the subject is extensive, this will be “Part 1”, dealing with food, drinks, alcohol & tobacco. More do’s and dont’s are coming….


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Eating healthy is one of the best things you can do to your baby, and to yourself! There is not a specific diet for pregnancy; you should just follow a healthy, varied, balanced diet: plenty of fruits, grains and vegetables, but also dairy products and meat, which provide iron, calcium, vitamins and proteins. You don’t need to eat for two! Actually, if you have a normal weight, only a few extra calories a day are needed while pregnant: none during the first trimester, about 300 the second, 450 the last trimester!

Try to eat frequent and small meals, and avoid eating a copious meal before bedtime. Although sweets, fatty or processed food should not be in your every day diet, don’t feel bad if you get occasionally tempted! In any case, pay attention to quality, but also to quantity: excessive weight gain may put you at risk of having gestational diabetes, pregnancy-induced hypertension or delivering a macrosomic (too big) baby…Not to mention that you will suffer to lose those extra kilos after birth!

Herein you will find some things you need to know about eating and drinking during pregnancy:

Meat & Eggs

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Meat is an excellent source of protein, iron, vitamins and minerals. But you should only eat well-cooked meat. Forget about carpaccio, steak tartare or saignant!

Eating undercooked or raw meat can lead to toxoplasmosis, a severe infection that may harm your baby. Uncooked cured meat, such as salami or prosciutto should also be avoided. Liver and liver products (such as pate) contain high levels of vitamin A, which is toxic for the baby. Indeed, a single serving of cow’s liver contains three times the recommended daily amount of vitamin A allowed in pregnancy, so even if liver is considered to be a healthy food, rich in proteins, iron and vitamins, stay away from it, or consume it no more than once a month.

Undercooked meat, especially poultry can carry salmonella, which may cause a very severe form of food poisoning, so pay special attention to cook well your chicken. Since Salmonella is also present in eggs, the consumption of raw or partially cooked egg is discouraged (this includes homemade mayonnaise, tiramisu, etc).

Fish & Seafood 

Had sushi for lunch last Saturday. It was delicious.

Fish is an excellent source of proteins, vitamins and the valuable omega 3 fatty acids, which boost your baby’s brain and eye development. However, you should avoid certain fishes, such as shark, swordfish, king mackerel, tilefish, and tuna. These fishes are contaminated with large amounts of mercury, which can be toxic for your baby. To see more details about mercury levels in fish and allowed servings, please click here.

Raw fish and seafood may contain harmful bacteria or viruses. Therefore, do not eat raw fish (includes some varieties of sushi and sashimi) or raw oysters. Octopus, calamari, shrimp are fine as long as are properly cooked. With smoked fish (such as salmon and trout) the opinions are divided: while it is considered to be safe by some experts, others advise against it due to the possibility of contamination with listeria, a bacterium potentially harmful for your baby.

Cheese & Milk

Cheese is a great source of calcium and vitamins, so go ahead and eat cheese as long as it is made of pasteurised milk. You should not eat soft cheeses such as brie, camembert, chevre, roquefort, which may grow the rare, but dangerous listeria. Check the packages, where it usually states states if the cheese is made with raw or pasteurised milk, and avoid homemade cheeses. Hard cheeses are fine. For the same reason, the milk you drink should always be pasteurised.


There is some (controversial) evidence that having more than 200 mg of caffeine a day may put you at risk of miscarriage or having a baby with low birth weight. This means that you may drink up to two cups of instant coffee or 1 cup of brewed coffee a day. Don’t forget other sources of caffeine, such as tea, cola, energy drinks or chocolate. For caffeine content of different beverages, please click here.

Herbal teas

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Herbal or natural doesn’t necessarily mean “safe”. Most teas are thought to be safe in pregnancy, as long as you don’t drink large amounts. Green tea contains caffeine, so do not exceed the recommended limit of 200 mg of caffeine per day (see above).

There are a couple of teas that you better avoid: Sage tea may be linked to miscarriage and high blood pressure. Parsley tea may increase the risk of miscarriage. Valerian is also best avoided, as well as chamomile in large amounts. Raspberry leaf tea may cause contractions, so do not consume it in early pregnancy, but it may be fine to drink during late pregnancy.

Artificial sweeteners

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In general, artificial sweeteners seem to be safe to have in pregnancy, they are though recommended with moderation. Stevia and sucralose should be preferred. Aspartame seems to be safe with moderate consumption, but it should be avoided by anyone with a rare disease called Phenylketonuria (PKU) or by persons with high levels of phenylalanine in blood. Saccharin and cyclamate have been possibly linked to same types of cancer, so they are best avoided in pregnancy.


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Alcohol in large amounts is highly toxic for the unborn baby. For light (social) drinking, the data has been contradictory. According to the British organisation NICE, although there is uncertainty regarding a safe level of alcohol consumption in pregnancy, at this low level there is no evidence of harm to the unborn baby: no more than one or twice a week, 250cc beer or 1 shot (25 ml) spirit or 2 small (125 ml) glasses of wine. Nevertheless, NICE recommends to avoid alcohol consumption during the first trimester due to a possible increased risk of miscarriage.

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The dangers of smoking have been widely established. Smoking during pregnancy puts you at higher risk of having a baby with low birth weight, as well as stillborn, sudden infant death syndrome, miscarriage, premature labor and placental abruption. Moreover, later evidence incriminates smoking of causing birth defects. See more information here. The risk includes even secondhand smoke. If you are pregnant and you keep smoking, discuss with your doctor the options you have to quit as soon as possible…



American Family Physician: Evidence-Based Prenatal Care: Part I. General Prenatal Care and Counseling Issues. April 2005, USA. http://www.aafp.org/afp/2005/0401/p1307.html
American Family Physician: Evidence-Based Prenatal Care: Part II. Third-Trimester Care and Prevention of Infectious Diseases. April 2005, USA. http://www.aafp.org/afp/2005/0415/p1555.html
ACOG: FAQ – Nutrition During Pregnancy. September 2013, USA. http://www.acog.org/Patients/FAQs/Nutrition-During-Pregnancy
NICE: Antenatal Care- Routine Care for the Healthy Pregnant Woman. March 2008, UK
HAS: Comment mieux informer les femmes enceintes? Avril 2005, France


Photo credits

1.Getty images; 2.media1.onsugar.com; 3.alachia, Flickr.com; 4.Back East Photography, Flickr.com; 5.Susanne Nilsson, Flickr.com; 6.Steve Nodgrass, Flickr.com; 7.Luz Bratcher, Flickr.com; 8.emdot, Flickr.com; 9.Shrikant Nigam, Flickr.com