5 Ways Stress Can Affect a Pregnancy

One in eight babies born in the United States each year will be premature [source: CDC]. In medical speak, this means that he or she will be born at less than 37 weeks gestation. There are lots of different reasons why babies are born prematurely, but many researchers believe that women who experience high levels of stress while pregnant are at high risk for experiencing a preterm birth. There's a reason why pregnancy is supposed to last 40 weeks -- babies born before this often do not have fully formed organs. The earlier a baby is born, the greater risk the child has of experiencing anything from minor breathing problems to lifelong diseases such as cerebral palsy.

Stress normally causes our brains to secrete hormones, such as corticotropin-releasing hormone (CRH). In pregnant women, CRH also helps to regulate the length of a pregnancy, and the amount naturally rises near the end of the third trimester to stimulate contractions. A study published in the American Journal of Obstetrics and Gynecology in 1999 (and subsequent studies by the same team) revealed that women who delivered prematurely not only had very high levels of CRH early on in pregnancy, but they also reported high levels of stress.

Next, find out why stress can even be related to one of the worst things a woman can experience while pregnant.

It's every pregnant woman's nightmare -- the loss of her baby during pregnancy, known in the medical community as a "spontaneous abortion." As with preterm labor, there are a host of reasons why some women experience miscarriages, and sometimes, there's no explanation at all.

However, there have been some studies indicating a link between miscarriage and high levels of stress, especially early in the pregnancy or just before conception. In the June 2003 issue of Endocrinology, researchers suggest that CRH isn't just released in the brains of highly stressed pregnant women; it's also released elsewhere in the body. The CRH targets a type of cell called a mast cell, which secretes chemicals that cause allergic reactions.

Apparently, one of these chemicals, tryptase, "prevents the production of membranes to develop the embryo and disrupts the whole architecture of the placenta that feeds the baby" [Source: WebMD].

In short, your pregnant body's reaction to stress can lead to a miscarriage if it happens early in pregnancy. A 2006 study showed that high levels of another stress hormone, cortisol, may affect levels of progesterone, which impacts uterine growth and other aspects of pregnancy [source: National Academy of Sciences of the USA]. So, not only should you try to avoid chronic stress while pregnant, but you should also focus on it early in your pregnancy.

Some babies are just born small, but they're otherwise considered healthy. Other babies are underweight because they didn't get enough nutrients to grow properly. It's not just because their mothers didn't eat right, either. In the next section, learn about the connection between low birth weight and stress.

Birth weight is an important statistic -- it's right there on the announcements next to name, length, date and time of birth. It's also important from a medical standpoint, although of course there's a wide range of what's "normal" and what's low. A baby is considered to be of low birth weight if he or she weighs less than 5 pounds, 8 ounces (2,500 grams) at 37 weeks. Some babies are just small and don't have any problems associated with their size, but others have low birth weights because they experienced intrauterine growth restriction (IGR) -- they didn't get adequate nutrition while in the womb. Babies with low birth weight are at greater risk for health problems like hypoglycemia (low blood sugar) and must be closely monitored to ensure that they are growing at a normal rate.

A baby can have IGR even if the mother ate adequately while pregnant. Stress hormones such as epinephrine, norepinephrine and cortisol can all cause blood vessels to constrict, and this potentially includes the blood flow to the baby via the umbilical cord. In this case, the fetus may not be absorbing enough nutrients from the mother's body. Often, the potential for low birth weight is identified in utero, and your doctor can suggest ways to change the behaviors that may be causing it -- such as cutting down on your stress levels.

Next, we'll look at how stress can increase the risk of infection during a pregnancy.

In addition to directly causing problems during pregnancy, the hormones produced by stress can also weaken your immune system. People who are highly stressed are in a constant state of alert, but the burst of hormones like cortisol involved in the fight-or-flight response is supposed to be short-term. Chronic stress, however, can result in reduced numbers of cells that fight off viral and bacterial infections. The stress response can also cause the nervous system to secrete substances that bind to white blood cells (which defend the body from disease) and make them less effective. Pregnant women already have lowered immune systems, so stress has even more of an impact on them. This equals an increase in illnesses that your body would normally be able to fight off.

Often, pregnant women can't take the same kinds of medications that would normally bring them quick relief when they're sick, so illnesses can last longer or they're more likely to have to suffer through some of the symptoms. Many different kinds of ailments can impact your pregnancy, as well. The flu, for example, is more likely to turn into pneumonia when you're pregnant -- just when you already have pressure on your lungs due to your growing belly and need more oxygen to support your baby.

In addition, you may also be more vulnerable to uterine infections when you have a compromised immune system. These may involve the placenta and amniotic sac and can be extremely dangerous. The treatment is high doses of antibiotics and inducing labor as soon as it is safe to do so. Uterine infections can interfere with the organ's ability to contract; severe ones may lead to blood clots. The baby can also be infected -- rarely, he or she may develop sepsis (infection in the bloodstream) or conditions like cerebral palsy.

It may surprise you to learn that chronic stress during pregnancy can have effects that you may not even notice until after you've given birth. Read on to find out how your stress can become your baby's stress.

So far, we've only looked at the near future -- things that stress can do during the actual pregnancy or problems that become apparent immediately after the birth of the baby. However, some researchers think that chronic stress during a pregnancy can result in issues that may not manifest until later in life. Stress may affect the development of the baby's brain when the high levels of hormones cross into the placenta. These problems may be emotional, behavioral or physical. Stress in pregnant women, especially in the first trimester, may result in irritable, anxious babies [source: Medicine Net].

Stress can also cause behavioral problems. And once the baby is born, the child may be more vulnerable to a wide array of stress-related issues [source: MedicineNet]. This can mean learning difficulties and slower development. It may even predispose your baby to diseases such as heart disease, obesity and type II diabetes -- the conditions that stress can create or exacerbate in you, as well.

Although we've discussed some potentially serious conditions, keep in mind that the links between stress and pregnancy are still being formed, and only the most extreme stressful situations are likely to cause problems. When you're pregnant, everything you do can affect your baby in some way, so add "keeping down stress levels" to your pregnancy health checklist.