Miscarriage Research – Causes and Prevention- THE 411

What Causes Miscarriage


What causes miscarriage:

  • chromosomal abnormalities of the fetus (causes 50% to 80% of first trimester miscarriages)
  • feeling stressed (associated with a 200% higher risk of miscarriage) 
  • low folate levels (47% higher risk of miscarriage) 
  • having both low folate and low vitamin B6 levels (causes a 310% increased risk of miscarriage) 
  • low magnesium levels 
  • low phosphorus levels 
  • low selenium levels 
  • low beta carotene levels 
  • low vitamin B12 levels 
  • low vitamin B6 levels 
  • low vitamin C levels 
  • low vitamin E levels 
  • low vitamin K levels 
  • high calcium levels 
  • high butter intake (100% increased risk of miscarriage) 
  • high oil intake (causes a 160% higher risk) 
  • eating too many or too few calories 
  • exercising one hour a day or more during the first 18 weeks of pregnancy (270% higher risk of miscarriage; however, there are opposing studies regarding exercise) 
  • exercising more than usual during implantation (causes a 150% higher risk of miscarriage) 
  • having a menstrual cycle longer or shorter than 30-31 days (causes a 200% higher risk) 
  • ovulating before day 11 (causes 122% higher risk of miscarriage) 
  • ovulating after day 16 or before day 12 (100% increased risk) 
  • high blood glucose 
  • high insulin levels (27% of women with recurrent miscarriage are insulin resistant) 
  • being overweight (causes a 67% higher risk of miscarriage) 
  • being underweight (causes a 70% increased risk) 
  • being 30-35 years old (12% increased risk)
  • being 35-39 years old (causes a 39% to 75% higher risk) 
  • being over 40 years old (162% to 400% increased risk)
  • having a partner over 35 years old (causes a 60% increased risk) 
  • needing more than one year to conceive (100% increased risk) 
  • having had an induced abortion in the past two years 
  • having had previous miscarriages (24% chance after 2 miscarriages; 87% after 7 miscarriages) 
  • high homocysteine levels 
  • having PCOS (contributing factors may actually be responsible for miscarriage) 
  • high testosterone levels 
  • high free testosterone levels (all subjects with free testosterone 1.30% and higher miscarried, none lower than .70% miscarried)
  • low progesterone levels (found in 17% to 35% of women with recurrent miscarriage) 
  • high estrogen levels (even in normal range) 
  • high FSH levels (even in normal range) 
  • high LH levels (even in normal range)
  • high prolactin levels (even in normal range) 
  • low SHBG levels 
  • having Factor V-Leiden gene mutation (causes a 1% higher risk of miscarriage) 
  • having the MTHFR gene mutation (450% to 530% increased risk) 
  • having a partner with the MTHFR gene mutation (130% higher risk)
  • having thyroid antibodies (causes a 173% increased risk of miscarriage) 
  • having a proinflammatory immune milieu 
  • having a high Th1/Th2 ratio 
  • chromosomal abnormalities (causes up to 80% of miscarriages)

Many of these traits can be altered. Each topic on this website includes research regarding how to improve one’s status without medical intervention.

How to prevent miscarriage:

  • consume chocolate (causes a 17% lower risk of miscarriage) 
  • consume dairy products daily (leads to a 33% lower risk of miscarriage) 
  • consume cheese (causes a 50% reduced risk) 
  • consume milk (40% lower risk) 
  • consume eggs (causes a 30% reduced risk) 
  • eat a high fiber diet 
  • eat fruit (causes a 46% to 70% lower risk of miscarriage, depending on the study) 
  • eat fish (leads to a 30% lower risk of miscarriage) 
  • eat poultry or fish twice a week (leads to a 15% lower risk) 
  • eat vegetables (causes a 40% reduced risk of miscarriage) 
  • conceive either one day before ovulation or on the day of ovulation (57% lower risk) 
  • extend your period to longer than 5 days (causes a 60% reduced risk of miscarriage) 
  • make it to 7 weeks pregnant with a visible fetal heartbeat (causes overall risk to drop to 5%) 
  • have morning sickness (70% lower risk of miscarriage; risk goes down as severity of nausea goes up) 
  • feel happy (causes a 60% lower risk) 
  • consume flaxseed (causes a 64% lower risk in cows) 
  • consume fish oil 
  • exercise (lowers risk of miscarriage of a healthy fetus by 40%; however, there are opposing studies) 

Studies show the overall risk of miscarriage to be around 20%. Once a gestational sac has been observed, the chance of miscarriage decreases to around 13.5%. After a heartbeat is seen, the odds improve even further, and the chance of miscarriage decreases to 9.4% at 6 weeks and a mere 0.5% at 9 weeks.

However, miscarriage continues to affect many women, and so there has been considerable research regarding the particular causes. What causes miscarriage remains unclear and certainly much is left to be elucidated. That being said, here are some findings regarding the most common causes of miscarriage:

Chromosomal abnormalities: The most common cause of miscarriage seems to be a failure in cellular division which results in an abnormal number of chromosomes. This has been estimated to cause up to 80% of miscarriages. Although it has been assumed by some that there is little that can be done to prevent these miscarriages, certain factors increase one’s odds of having a chromosomal defect. Smoking and low levels of folate in both mother and father have been associated with a higher risk of chromosomal defects. Thus, elimination of smoking and supplementation of folic acid may reduce one’s risk of miscarriage from these causes. Also, an acidic PH level causes chromosomal defects in mice, so it could be postulated that adopting an alkaline diet might reduce the chances of miscarriage. Another factor may be the time to fertilization after ovulation. In hamsters, mating too late after ovulation results in higher rates of aneuploidy and triploidy, which causes miscarriage. Finally, although maternal age has been associated with chromosomal abnormalities, recent research has suggested that it is actually high levels of FSH resulting from a reduced egg supply that is the culprit and may cause miscarriage. Thus natural methods of reducing FSH, such as increasing dietary fiber intake, or consuming soy or vitex may be helpful in preventing miscarriage.

Thrombophilia: Of the known medical causes of miscarriage, thrombophilia is among the most common. In women with no physical, hormonal or chromosomal abnormalities, 92% have been found to have thrombophilia. Once thrombophilia has been identified by a doctor, the prescription medication heparin has been shown to reduce the chances of miscarriage in women with thrombophilia to that of healthy controls. To prevent hypercoagulation, reducing dietary fat, stress, and high BMI may be of some help.

Progesterone: Luteal phase defect is found in up to 35% of women with repeat miscarriage. Inadequate progesterone production is thought to be a contributing factor to luteal phase defect. Likewise, low progesterone may cause miscarriage. 91% of pregnancies with progesterone lower than 15 ng/ml end in miscarriage. Increasing progesterone may reduce one’s chances of miscarriage. In women with recurrent miscarriage, women who were given supplemental progesterone reduced their odds of miscarriage by 62% versus women who received placebo or no treatment. One may be able to increase their levels of progesterone naturally by supplementing with either vitamin C, vitamin E, L-arginine, beta carotene, vitamin B6, vitex, black cohosh (on cycle days 1 to 12) or selenium, as these have all shown positive results in various studies. Also, consuming dairy products, reducing obesity, avoiding overeating and saturated fat and improving insulin sensitivity have been shown beneficial to progesterone levels. Likewise, many of these solutions have been associated with a lower risk of miscarriage.

Diet: Avoiding poor dietary choices may be beneficial in avoiding miscarriage. While there have only been a handful of studies regarding which food choices influence one’s risk of miscarriage, the findings have been significant. One study found that those who consumed the most butter doubled their chances of miscarriage over those who consumed the least, even after adjusting for BMI. Likewise, those with the highest levels of oil consumption had a 60% higher chance of miscarriage. High levels of dietary fat may cause miscarriage because they cause higher levels of inflammation and blood coagulation, or because they deleteriously affect hormone production. For those wanting to avoid miscarriage, consuming fruit may be one of the most powerful tools easily available. Women with the highest level of fruit consumption reduced their chance of miscarriage by 70%. Similarly, women with the highest level of vegetable consumption had a 40% lower chance of miscarriage. While meat consumption per se does not seem to cause miscarriage, those who consumed the most fish reduced their chance of miscarriage by 30% and those who consumed the most eggs also reduced their risk of miscarriage by 30%. Consuming dairy products every day has been shown to reduce the odds of miscarriage by 33%. This may be due to dairy’s ability to reduce inflammation or increase levels of estrogen. Surprisingly, eating chocolate seems to reduce the odds of miscarriage by 19%.

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