The Pregnant Brain

Are evaluated stress hormones a part of preparing for motherhood?

Pregnancy is often called “the other state.” And it definitely is. This unique transition phase changes your body, personality, your life forever. It is emotional, exciting and often brings a sum of concerns. Extended, intense stress is unsafe and harmful for mother and baby, but stress at some degree is commonly expected during the pregnancy. Is this an evolutionary feature of the pregnant brain?

Throughout the different stages of pregnancy various physical and psychological processes occur. And while they can sometimes appear to be intense, they are perfectly normal and do have their aim. Mother Nature arranged it.  For example, the well-known phenomena called “momnesia” – memory and concentration problems some moms-to-be experience. Some say that this is an evolutionary outcome that helps the future mother to focus on the baby by neglecting irrelevant information. But there are some studies that showed no difference in cognitive functioning between pregnant and non-pregnant woman in performing cognitive tasks. And the conclusion is simple – the pregnant brain is not becoming stupid, but just adapting to shifts a woman’s body and mind experience.

But what about the stress during the prenatal period and its impact? Negative effects of stress are a fact, especially during pregnancy. So why didn’t nature prepare a pregnant brain to be stress-free? Some studies shows that it did, in a somewhat unexpected way.

Stress hormone levels rise during pregnancy, but the underlying mechanism is much more complicated than it looks at first site. The rise in these hormones result in helping the fetus develop, additionally protecting it by lowering the future mothers’ responses to acute stressors, and by backing up positive maternal behavior. Gwen Dewar, Ph.D., a biological anthropologist sums the recent study research on this issue:

“During the second trimester of pregnancy, circulating levels of corticotrophin-releasing hormone (CRH) increase exponentially but it remains inactive because pregnant women produce large quantities of a CRH-binding protein (“CRH-BP”) that prevent CRH from being recognized and used by receptors,” Dewer explains. The situation changes in the last three weeks – CRH continues to grow but the CRH-BP starts to decrease, making one of the main stress hormones – cortisol to rise two to three times higher than regular. And while in non-pregnant persons these high levels of cortisol are linked with Cushing’s syndrome and melancholic depression, it seems that they serve the fetus by having a role in brain and lungs development.

The rising CRH protects the fetus in early pregnancy by inhibiting the mother’s immune system to attack the fetus. Further on, it helps the maturation of  internal organs, as well as it has its role in regulating blow flow between the placenta and the fetus.

Additionally, this fine-tuned mechanism of evaluated hormones may result in lowering mothers-to-be responses to acute stressors and prepare her for more attentive motherhood. A number of studies showed that mothers with higher cortisol levels demonstrate more positive maternal behavior and are more sensitive to their infants’ body odors, summarizes Dewar.

Mood shifts that some pregnant women experience, as well as some postnatal mood disorders are possibly linked to this hormonal loop as well, but more research is needed to conclude so, especially because it is hard to single out one factor when it comes to the interaction between mind and body.

Woman’s whole being is definitely following somewhat altered ways of functioning during this “other state” and medical and psychological science on pregnancy is progressing fast. And while the science is making an effort to untangle unresolved questions, focus your pregnant brain on the joys of pregnancy.

By Milica Zujko

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