During pregnancy, blood volume increases by 50%, and the heart and lungs work more intensively. The immune system balances between protecting the mother and the fetus, and the brain restructures to form attachment.
The external changes in a pregnant woman’s body are merely the tip of the iceberg of a profound systemic transformation. Over nine months, the body undertakes a task comparable to preparing for a marathon – except this “marathon” spans months, and the finish line, childbirth, demands its own specific resources. Scientific insights into the physiological shifts during pregnancy are detailed in this UNN article.
Increased Blood Volume
One of the initial and most noticeable alterations is the expansion of blood volume. A woman’s total blood volume escalates by approximately 1.5 liters, reaching a level 50% higher than pre-pregnancy by the time of delivery. A significant portion of this surplus volume is allocated to the uterus and placenta.
An interesting observation is that plasma volume expands more rapidly than the red blood cell count. This phenomenon leads to what is termed “physiological anemia of pregnancy” – where hemoglobin levels appear lower in tests. This is not a pathology but a consequence of blood dilution due to increased plasma volume. The body initiates this process as early as the fourth week of gestation.
Furthermore, a pregnant woman’s blood exhibits enhanced coagulability – a natural protective mechanism against blood loss during childbirth, yet it simultaneously raises the risk of thrombus formation. As explained in a comment to UNN by Dmytro Hovseiev, Head of the Department of Hospital Obstetrics and Gynecology and Postgraduate Education at the Bogomolets National Medical University, and a distinguished physician, pregnant women also experience elevated cortisol levels and an increased oxygen requirement.
Heart and Lungs: A Doubled Workload
A pregnant woman’s heart operates with considerably heightened intensity. The volume of blood pumped per minute increases, and blood supply to the kidneys and the utero-placental complex is enhanced. Concurrently, many pregnant individuals notice a drop in blood pressure.
Breathing patterns also undergo changes: respiratory depth increases by approximately 40%, and frequency by about 15%. This means a woman breathes more intensely, even at rest.
The Entire Body Adapts to Protect the Fetus
As indicated by Dmytro Hovseiev, pregnant women become more susceptible to infections. Researchers have found that the immune system of a pregnant woman operates in a delicate balance, protecting the mother’s body while simultaneously refraining from attacking the fetus. This is achieved by reducing the activity of certain immune cells and augmenting the function of others.
Other bodily systems also experience modifications. For instance, the thyroid gland enlarges, and the gastrointestinal tract slows down, leading to common pregnancy symptoms such as nausea, heartburn, and a feeling of heaviness after meals.
The brain, too, is altered – it undergoes a significant restructuring to facilitate the mother’s ability to recognize her infant’s needs and foster a stronger bond post-delivery. These processes are orchestrated by the same hormones: estradiol, progesterone, prolactin, and oxytocin. After childbirth, many of these changes gradually revert to their pre-pregnancy state.
“Pregnancy is a natural physiological process. The changes occurring in a woman’s body during a normal pregnancy are not indicative of illness. However, during this period, the body requires increased attention and care,” explains Dmytro Hovseiev.
Throughout pregnancy, the body’s primary objective is to carry and deliver a healthy child, often irrespective of the physical strain the woman endures. Consequently, the female body merits exceptional respect and care during this time. This includes preventive measures against potential exacerbations of chronic conditions and vigilant monitoring of even minor changes that might signify profound internal processes. Therefore, regular medical supervision during pregnancy is not a mere formality but a crucial method for distinguishing normal adaptation from conditions requiring intervention.