Up to 30 percent of all pregnancies end in miscarriage, defined as pregnancy loss before the 20th week of pregnancy. Half of all miscarriages have unexplained causes, although certain factors such as genetic defects, damage to the placenta, hormonal problems and infections increase the risk of pregnancy loss. The consumption of alcohol, nicotine and other drugs can also lead to a miscarriage. Such an event is traumatic for expectant mothers and can lead to depression and anxiety. Are there any external influences such as the time of year which may also play a role? Some research suggests that there is an increased risk of miscarriage during the summer months.
Increased Risk of Miscarriage in Summer
A recent study by researchers at the School of Public Health in Boston found that the risk of miscarriage (particularly for an early miscarriage within eight weeks of pregnancy) increased by 44 percent in North America at the end of August compared to the end of February, suggesting that possible links between extreme heat and miscarriage should be investigated. The study was published in the journal Epidemiology. The risk of miscarriage in each week of pregnancy was 31 percent higher at the end of August compared to the end of February. From a geographic perspective, the results showed that pregnant women in the South and Midwest, where summers are hottest, were more likely to experience this loss in late August and early September, respectively.
For the study, researchers focused on 6,104 participants from the Pregnancy Online Study (PRESTO) who became pregnant within 12 months of enrollment. The women provided information about each type of pregnancy loss, the date of the miscarriage, and the gestational week at the time of the loss. The researchers found that the risk of miscarriage, particularly early preterm birth before eight weeks of pregnancy, was highest in the summer. These results suggest that additional research is needed to understand the potential roles of extreme heat and other environmental or lifestyle stresses from hot weather in unexpected pregnancy loss.
The Dangers of Caffeine
Even if the morning cup of coffee is important for many women, heavy caffeine consumption can be problematic during pregnancy. High doses of daily caffeine during pregnancy — whether from coffee, tea, caffeinated soda, or hot chocolate — cause an increased risk of miscarriage, according to researchers at Kaiser Permanente Research. The study looked at 1,063 expectant mothers and how their caffeine consumption behavior affected their pregnancy. They found that women who consumed 200 mg or more of caffeine per day (two or more cups of regular coffee) had twice the risk of miscarriage than women who did not consume caffeine.
Women who consumed less than 200 mg of caffeine daily had a more than 40 percent increased risk of miscarriage. The reasons why caffeine can harm a fetus have been suspected for some time. Caffeine passes through the placenta to the fetus but can be difficult for the fetus to metabolize due to the underdeveloped metabolic system. Caffeine can also affect cell development and reduce blood flow to the placenta, which can result in an adverse effect on fetal development. However, research has come to conflicting conclusions. Some current research suggests that 200 mg of caffeine per day is considered safe and does not increase the risk of miscarriage. According to the WHO, consuming less than 300 mg of caffeine per day (about 2 cups of coffee) is associated with minimal health risks for both mother and child. Still, it’s advisable for expectant mothers to speak to their doctor to determine which amount of caffeine is safe to minimize any potential health risks.
How Poor Sperm Quality Affects the Risk of Miscarriage
But not only the health of the mother plays a role with regard to the risk of miscarriage. In fact, research shows that recurrent miscarriages can also be father related and linked to poor sperm quality. Scientists from Imperial College London studied the sperm quality of 50 men whose partners had suffered three or more consecutive miscarriages. The study, published in the journal Clinical Chemistry, found that the sperm of the people involved in the study had higher levels of DNA damage compared to men whose wives did not have an abortion. The study team hopes these results may open new avenues to find treatments that reduce the risk of miscarriage. In the past, it was mostly assumed that recurrent miscarriages were caused by maternal health problems such as infections or immune problems. In fact, also the father can be responsible. Previous research suggests that sperm play an important role in the formation of the placenta, which is crucial for delivering oxygen and nutrients to the fetus.
In the study, the team analyzed the sperm cells of 50 men. They then compared the results to the sperm health of 60 male volunteers whose partners had not miscarried. The analysis found that sperm from men with partners who had had repeated miscarriages had twice as much DNA damage as the control group. The research team suspects that this DNA damage could be triggered by so-called reactive oxygen species. There are molecules made by cells in semen (the fluid that contains sperm cells) to protect sperm from bacteria and infection. However, in high concentrations, the molecules can cause significant damage to the sperm. What was amazing, ist the fact, that the sperm of men whose wives had suffered a miscarriage contained four times more reactive oxygen species than the control group. There is also evidence that obesity can affect sperm health, possibly because high levels of body fat can trigger an increase in reactive oxygen species. The men whose partners had miscarried were slightly older than the control group – with an average age of 37 compared to 30 – and slightly more obese.
Even though there are many factors that influence pregnancy, it is important for expectant mothers to keep calm. A healthy diet, moderate physical activity, stress reduction and regular check-ups with your doctor are the most important measures to ensure a healthy pregnancy and to reduce the risk of miscarriage and other complications.