Physiological Changes in Pregnancy: How Your Body Adapts
Learn how your body changes during pregnancy and why understanding these normal shifts matters for your care.
In short: The mother’s body adapts to pregnancy with normal changes: blood volume and the output of the heart rise by about 50%, blood pressure falls, the diaphragm rises, kidney filtration increases by about 50%, digestion slows, causing constipation and heartburn, and the pelvic ligaments loosen. Knowing these changes helps to tell normal symptoms of pregnancy from signs of illness.
Pregnancy is a truly special physiological state, during which a woman’s body undergoes extensive changes to adapt to her growing baby and support a healthy pregnancy.
These changes also prepare the mother’s body for childbirth and breastfeeding.
Every organ system is affected, mainly due to placental hormones and maternal gland activity.
Why is it important to understand the physiological changes of pregnancy?
Knowing what counts as a normal pregnancy change helps distinguish it from a pathological one — which is why your obstetrician monitors these changes closely throughout your pregnancy.
- Hormonal changes:
- hCG hormone: supports the corpus luteum in early pregnancy to maintain progesterone production
- progesterone: relaxes uterine muscles and helps prevent premature contractions
- estrogen: promotes uterine growth, breast development, and increased blood flow
- hPL hormone: modifies maternal metabolism
- relaxin: softens the cervix in preparation for delivery
- Cardiovascular system changes:
- increased blood volume by 50%
- increased cardiac output by 50%
- decreased systemic vascular resistance
- blood pressure falls slightly in the first half of pregnancy and returns to its usual level near term (a reading of 140/90 or higher is not normal and should be checked)
- Respiratory system changes:
- increased tidal volume
- increased ventilation per minute
- respiratory alkalosis
- elevated diaphragm due to the enlarged uterus
- improved oxygenation
- Renal system changes:
- increased blood flow to the kidneys
- increased glomerular filtration rate by 50%
- mild glucose in urine
- dilatation of the ureters
- Gastrointestinal system changes:
- nausea and vomiting
- reduced motility
- constipation
- heartburn
- increased appetite
- Hematological changes:
- increased clotting factors, leading to a tendency toward thrombosis
- a mild fall in haemoglobin concentration because plasma increases more than red cells (haemoglobin below 11 g/dL in the first trimester or below 10.5 g/dL later in pregnancy is true anaemia and should be treated)
- increased blood cell mass
- Musculoskeletal changes:
- relaxation of pelvic ligaments
- lumbar lordosis
- loosening of pelvic joints
These changes can lead to lower back pain and altered posture, which many pregnant women notice as pregnancy progresses.
- Skin changes:
- increased pigmentation
- increased sweating
- increased activity of sebaceous glands
- palmar erythema
Understanding these normal changes helps your obstetrician tell the difference between healthy pregnancy physiology and a developing complication, so you and your baby receive the best possible care throughout pregnancy.
If you have questions about the changes you’re experiencing during pregnancy, Dr. Najeeb Layyous and his clinical team are here to guide you with attentive, experienced care at every stage.
Dr Najeeb Layyous F.R.C.O.G
Consultant Obstetrician, Gynecologist and Infertility Specialist
The finest doctor in Jordan — may God bless him and his whole medical team. A doctor in every sense of the word. I advise anyone planning a pregnancy to visit Dr. Najeeb Layyous. His manner is wonderful, always smiling, with the highest ethics; he gives every patient her due, and the patient’s comfort matters most to him. We had been to many doctors and none understood and treated my case except him. Special thanks to him and the whole team, and to Dina in particular — a lovely person. I recommend anyone considering IVF or pregnancy to visit his clinic.