Maternal Adaptation to Pregnancy – From The Very Beginning

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Eat For Baby is all about empowering women entering their pregnancy journeys to take care of their health and wellbeing. Your body undergoes many changes to support the growth of a whole new human being, and we believe it is important for all women to understand the workings of their bodies and the pregnancy-induced changes, many of which we don’t see.

This post will explore the changes that occur in every mother's body as she grows her baby; what causes these changes; the symptoms you might experience as a consequence; and the role of good nutrition before, during and after pregnancy for maternal wellbeing and pregnancy success. We think understanding how your body works, why it is doing what it is doing and how this might affect how you feel, will leave you feeling empowered. We want to arm you with the know-how to maintain your health and wellbeing throughout your pregnancy journey. We encourage women to listen to their bodies, acknowledge how they are feeling and respond. Pregnancy is an opportunity to tune into our intuition and really get to know our bodies.

Your body prepares for pregnancy every menstrual cycle

Every organ system in your body changes to support the growth of your baby. Many of these changes start almost immediately after conception. Human chorionic gonadotropin or hCG is a protein produced by the embryo and its role is to maintain the corpus luteum – the remnant of the follicle that ruptured to release the egg for fertilisation. hCG is what is measured in pregnancy tests. The corpus luteum is a temporary structure in the ovary that produces progesterone after ovulation. If no rescue signal (i.e. hCG) is received by the ovary, this indicates that there was no fertilisation (the egg did not meet a sperm) and the corpus luteum degenerates. Progesterone levels then fall, leading to the breakdown of the endometrium (the lining of your uterus that builds up and sheds each menstrual cycle) and a period – signalling the start of a new menstrual cycle. Did you know that humans are one of only a very small number of mammals that actually shed their endometrium and have a menstrual cycle? That’s a story for another day, but it’s important to understand how uniquely human our pregnancy journey is.

If the corpus luteum does receive a rescue signal from the embryo i.e. hCG, it continues to produce progesterone for the first 9 weeks of pregnancy. Progesterone is critical for implantation success because it maintains and promotes the growth of the endometrium, preventing menstruation and loss of the pregnancy. After 9 weeks of pregnancy, the placenta takes over the production of progesterone.

Your baby makes sure it gets what it needs

Mum’s role during pregnancy, from the fetus’s perspective, is to provide oxygen and nutrients, remove waste products, regulate temperature and provide protection from the external environment so that the fetus can grow and survive. Sounds a bit like the role of a mum once the baby is born / becomes a toddler / even a school aged kid (dare I say, teenagers too?). “Mum, I’m hungry”. “Mum, I’m finished with this, can you please take it?”. “Mum, I’m cold” . “Mum, I’m scared”.

From the moment of conception, the embryo starts communicating with their mum, maximising the embryo’s chances of survival. There is an intricate exchange of information between the mother, the placenta and the fetus to achieve pregnancy success.

Your hormones get baby what it needs

Many of the physiological changes that occur during pregnancy are driven by the hormones estrogen and progesterone. Estrogen and progesterone are sex steroids, produced by a series of reactions in the ovary. Before pregnancy, their synthesis is controlled by gonadotropin-releasing hormone (GnRH), released from the hypothalamus in the brain. At the pituitary gland (at the base of the brain), GnRH stimulates the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) into the circulation. During pregnancy, the increase in estrogen production, first by the corpus luteum and later by the placenta suppress the release of LH and FSH, so that no more follicles are matured in the ovary (mum doesn’t need to be investing her resources in another baby just yet!).

Estrogen and progesterone enter the bloodstream and affect just about every organ system. Over the next few posts, we will explore in detail the effects these hormones have throughout your body during pregnancy.

One of the most powerful things we can do to support our body is to fuel it with nutrient rich, unprocessed foods. Check out our recipe page for delicious recipes that are ideal for women during their pregnancy journey. All are packed with nutrients, designed for the everyday home cook and can be enjoyed by the whole family.


Lecture - Maternal Adaptation to Pregnancy: Dr Hayley Dickinson, Monash University
Endocrinology and Reproduction in Textbook of Medical Physiology, Guyton and Hall

Written by

Dr Hayley Dickinson, BSc (hons), PhD

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