Common causes of infertility and miscarriage

Common causes of infertility and miscarriage

Getting pregnant can be more complicated than many of us think. Today in the US, about 10% of us struggle with infertility and have a hard time getting or staying pregnant, which can be pretty frustrating. Since this is so common, let’s go over the common reproductive health issues that aren’t frequently talked about and how they can affect you.


PCOS (Polycystic Ovarian Syndrome) is a reproductive health issue that affects 1 in 10 women of childbearing age. People with PCOS usually struggle to get pregnant but aren’t automatically infertile. PCOS creates an imbalance in your reproductive hormones which leads to issues with your ovaries and menstrual cycle, including irregular, infrequent, missed, or prolonged periods.

The reproductive hormones that affect PCOS are androgens, insulin, and progesterone. Androgens are often referred to as “male” hormones, but some people with PCOS have higher levels of androgens. These higher androgen levels can prevent the ovaries from releasing a mature egg each menstrual cycle. It can also cause extra hair growth and acne, which are signs of PCOS. 

The insulin hormone manages your blood sugar and controls how your body changes food into energy. With PCOS, many people have insulin resistance, meaning their bodies don’t react to insulin intake the way they should. Insulin resistance is often associated with obesity, but its actual is unknown.

Finally, many people with PCOS don’t have enough of the progesterone hormone. Progesterone is the hormone made by the ovaries after an egg is released, so people with low progesterone levels are likely to experience irregular or long-lasting periods.


Endometriosis is a condition that affects the tissue lining the uterus. Typically, natural tissue grows on the inside of your uterus and sheds once a month when menstruation happens. With endometriosis, this tissue grows outside of the uterus, sometimes causing endometriomas (cysts) to form on the ovaries. Endometriosis affects around 11% of American women between 15 and 44 and makes it much harder to get pregnant.

Endometriosis affects fertility by producing abnormal cells and tissue that block the ovaries from releasing eggs as well as stops the tubes from working properly. One OBGYN reported that 40% of unexplained infertility comes from endometriosis, as it changes the hormonal environment and quality of the eggs.

It’s worth noting that many people with endometriosis do get pregnant without issues. However, pregnancy with endometriosis increases the chances of miscarriage, high blood pressure, and early birth. Many people with endometriosis report that they benefit from increased levels of progesterone during pregnancy and their symptoms are relieved. Others, however, find that the expansion of the uterus during pregnancy worsens their endometriosis symptoms and causes more discomfort.


Ectopic pregnancy

An ectopic pregnancy is a pregnancy in which the fetus develops outside of the uterus, typically in a fallopian tube. During a “typical pregnancy,” a fertilized egg attaches to the lining of the uterus. During an ectopic pregnancy, the fertilized egg grows outside the main cavity of the uterus. 

There are a few different types of ectopic pregnancies, depending on where the fertilized egg implants itself. In 98% of ectopic pregnancies, the fertilized egg implants in the fallopian tube. This type of ectopic pregnancy is known as a tubal pregnancy. Tubal pregnancies can be further classified on where in the fallopian tube the egg implants. In about 5% of tubal pregnancies, the egg grows in the fimbrial end of the fallopian tube. More commonly (80%), the egg will grow in the ampullary section. In 12% of tubal cases, pregnancy happens in the isthmus and increases the chances of hemorrhage.

Next, there are non-tubal ectopic pregnancies. Accounting for 2% of all ectopic pregnancies, non-tubal ectopic pregnancies occur when the egg implants in other areas such as the ovary, the cervix, or the intra-abdominal region. 

In very rare cases, one egg implants inside the uterus and the other implants outside the uterus. This is known as a heterotopic pregnancy. In some cases, the fertilized egg inside the uterus might still be viable, as long as hCG levels continue to rise. 

The three main signs of ectopic pregnancy are vaginal bleeding, missed period, and abdominal pain. Unfortunately, only around half of people with an ectopic pregnancy will experience all of these. These symptoms typically appear around 6-8 weeks into pregnancy.

One in every 50 pregnancies results in an ectopic pregnancy. People between the ages of 35 and 44 are especially at risk for ectopic pregnancy, particularly those who had one in the past. People with endometriosis are also at increased risk for ectopic pregnancies. This is because endometriosis can cause scar tissue to form resulting in a blockage in the fallopian tube. 

Chemical pregnancy

A chemical pregnancy is one that results in very early pregnancy loss, usually in the first few weeks. The name comes from the levels of hormone human chorionic gonadotropin (hCG) that are initially high enough to produce a positive pregnancy result on a pregnancy test but dip again before they can be visibly detected on an ultrasound. 

Most early pregnancy losses including chemical pregnancies are caused by chromosomal abnormalities that make it non-viable from the start. When the body recognizes this, it will naturally terminate the pregnancy soon after the egg implants. 

A chemical pregnancy is sometimes revealed when an early pregnancy test shows a faint positive result but later returns a negative result. The loss of a chemical pregnancy will typically happen about a week after your regular period was due. There are no real symptoms of a chemical pregnancy other than a late period, but you may experience cramping. 

If you struggle with infertility, you’re not alone. No matter how long you’ve been trying to conceive, it can be overwhelming, exhausting, and even discouraging. At Stix, we want to take the stress of buying pregnancy and ovulation tests off your shoulders. Sign up for a subscription today to be delivered right to your door so that buying tests is one less thing for you to worry about. 

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