What happens during pregnancy?
You’ve peed on a stick and those two little lines appear… and you’re now thinking, what happens next?! What happens during pregnancy?
From day one of pregnancy your body starts to change. Your hormone production begins to fluctuate, which then leads to physiological changes you’ll experience through the third trimester of your pregnancy and beyond. Not only is your body changing to accommodate a growing baby, there’s a baby growing inside you!
Your baby is significantly changing almost minute by minute in the womb. To be honest, fetal development is fascinating, and we STILL don’t fully understand how it all takes place inside the womb.
It can sometimes feel like an intangible concept, a growing a baby in the womb, because we’re unable to actually visibly see our babies develop day by day. The only measure of growth is the measurement of the growing abdomen. But undoubtedly the most amount of development is happening in our baby, as the body changes and adapts to their needs.
If you’re unsure about what to expect during pregnancy, and what’s happening as your baby grows month by month, you’re in the right place! Preparing for pregnancy builds your confidence in being able to adapt to your changing body. You’ll be providing yourself with the best possible foundation for a positive pregnancy experience.
Fetal Development: Your Growing Baby
It’s estimated to take approximately 40 weeks for your baby to fully develop and be ready for life outside of the womb. Scientifically speaking, the stages of a developing embryo are referred to the following:
The term ‘trimester’ is used when referring to development in relation to pregnancy. Each trimester ranges in length determined by gestational age as follows:
The gestation of a baby is measured from the time of conception until birth.
Being able to determine the exact date of conception is difficult, and almost impossible, so health care providers use gestational age of a baby measured from the first day of a pregnant person’s menstrual cycle.
This means the first two weeks of pregnancy, you’re technically not yet pregnant! This is the time your body prepares for pregnancy.
It’s important to understand that the age and stage of an embryo are considered independently of each other.
AGE – a measurement of time
STAGE OF DEVELOPMENT – an assessment of the level of physical development
Embryos will develop at varying rates depending on a variety of factors in the embryo’s environment. (Keep this in mind for later!).
Once an embryo becomes a fetus (baby), they’re able to survive outside of the womb at approximately 24 weeks gestation. However, a baby is considered to be full term at 37 to 42 weeks gestation.
The longer your baby remains in the womb, the longer they’re able to develop and prepare themselves for life outside the womb.
Development Week by Week
DIVIDING ZYGOTE / IMPLANTATION
Cell division begins 24-36 hours after conception. A fertilized egg will separate into two separate masses, the placenta and the forming embryo. The cells of the embryo form a blastocyst of three layers:
Ectoderm (nervous system)
Endoderm (digestive and respiratory systems)
Mesoderm (muscle and skeletal systems)
EMBRYONIC PERIOD
This is the most important period for the development of your baby’s brain. This is when the neural tube forms, at approximately four weeks after conception.
It will take around four more weeks for the basic spinal cord, brain, and central nervous to be established. Your baby’s head will begin to form around the fourth week, and by the fifth week, arm and leg buds will be developing.
By the end of the embryonic period, all organs will be established but the sex organs.
FETAL PERIOD
Synapses (connections of neurons in the brain to neurons in the rest of the body) begin to develop during this period.
You baby’s reflexes of the arms and legs begin to emerge. And by the end of the third month, the sex organs will begin to develop, and all your baby’s body parts will have formed.
The last two months of this period are when your baby will gain weight and prepare for life outside the womb!
What You May Experience
With every pregnancy will come a set of unique changes to the body. Some people will experience many signs and symptoms of pregnancy and others only a few. Here are some of the most common changes pregnant people experience:
Weight Gain
Fluid Retention
Stretch Marks
Hyperpigmentation
Moles & Freckles
Rashes
Being out of breath
Dizziness & Fainting
Other changes can sometimes be seen in:
Blood Pressure
Vision
Hair and nails
Taste and smell
Body Temperature
Eating Habits
Ability to Exercise
Some unattributed pregnancy symptoms you may also experience include fatigue, constipation, vivid dreams, confusion or forgetfulness, and mood swings. But no need to worry, these are normal and common for most pregnant individuals!
However, if you experience any of the following symptoms, you should contact your health care provider:
Vaginal bleeding
Sharp stomach pain
Extreme vomiting
Fever & Chills
Rash after a fever
Blurry vision
Sudden weight gain
Pain when urinating
Smelly odour to your vaginal discharge
Severe headaches
Baby is moving less.
Chest pain.
Swelling of the face, hands, legs or ankles
Hormone Changes
The hormonal changes caused by pregnancy are unique to everyone and will affect you both physically as well as emotionally.
The primary pregnancy related hormones are estrogen and progesterone. They are key reproductive hormones that fluctuate during the menstrual cycle to prepare the body for pregnancy. Once a person becomes pregnant, there is a sudden and dramatic increase in these hormones, where they continue to rise for the remainder of pregnancy until the body is ready to give birth.
Estrogen helps the uterus and placenta improve vascularization (growing blood vessels to improve oxygen and nutrient supply) and supports your developing baby in transferring of nutrients. This hormone is also believed to have an important role in helping your baby develop and mature.
Changes in progesterone causes a laxity and loosening of the muscles and joints. Increased levels of progesterone also causes internal structures to increase in size – such as the uterus.
The fluctuations of estrogen and progesterone during pregnancy affect your mood, contribute to the “glow” of pregnancy, alter the impact of exercise and physical activity on the pregnant body, but most importantly, help in the development of your baby.
Weight Gain & Fluid Retention
Pregnant people with healthy babies will gain varying amounts of weight during pregnancy. Your health care provider may assess your pre-pregnancy weight to determine your recommended amount of weight gain. But keep in mind, this is only a recommendation!
Weight gain during pregnancy is attributed to many factors as listed below. This additional weight can reduce circulation of blood and body fluids, typically in your lower limbs. Retaining fluids can lead to swelling of the lower limbs, hands, and the face.
This totals on average 25-35 lbs in weight gain, but remember, every pregnant person will gain varying amounts during their pregnancy – every pregnancy is unique.
Physical Activity & Exercise
The weight gain attributed to pregnancy listed above increases the workload on the body. It’s the primary reason your body may be unable to tolerate pre-pregnancy levels of exercise.
Your pregnancy hormones are increasing the laxity in your ligaments in order to accommodate your growing baby and preparing you for labour. This can cause:
Discomfort during exercise
Increase your risk for injury.
Round ligament pain.
You may find your enlarged uterus contributing to limitations in your exercise activities. These limitations can be frustrating but remember to give yourself grace, focus on your well-being and avoid the risk of becoming injured.
You know your own body’s limits!
Breast Changes
During pregnancy your breasts will begin to change in preparation to supply milk for your newborn baby. They may also be susceptible to hormonal changes resulting in skin pigmentation.
As the milk ducts in your breasts continue to expand, you may notice your breasts becoming larger, you may develop stretch marks as a result, and you may begin to leak colostrum as your body prepares for milk production.
But don’t worry if you don’t see the changes in your breasts. Not all pregnancy changes are experienced by all pregnant people!
You may experience the following changes to your breasts:
Darker and larger areolas
Darker veins
Increase in size
Tenderness or sensitivity
Nipples begin to protrude
Stretch marks
Leaking in the third trimester
Skin Changes
Your hormones and weight gain can be attributed to the skin changes you may experience during pregnancy. Most pregnant people experience some form of skin changes that are either temporary or permanent. Here are the most common:
HYPERPIGMENTATION
This is the darkening of your skin tone. It occurs on areas of the body such as your areolas, abdominal linea alba, genitals, and scars. The ‘mask’ of pregnancy is referred to as the darkening of the skin on your face.
Most hyperpigmentation resolves after birth.
Hyperpigmentation can also darken existing birth marks, freckles, and moles. Most of the time this darkening is benign, but if you notice changes in size, colour, or shape, it is best to notify your health care provider.
STRETCH MARKS
The most well known skin change related to pregnancy are stretch marks. They can affect up to 90% of pregnant people. These marks appear pinkish-purple and are a result of the physical and hormonal stretching of the skin. Although they may never fully disappear, they often fade in colour and intensity with time.
PREGNANCY-SPECIFIC SKIN CONDITIONS
There are pregnancy related skin conditions, like rashes and boils, that affect a small number of pregnant people. Most are harmless and resolve quickly, however it is best to notify your health care provider of any unexplained or bothersome skin changes.
Circulatory System
Your developing baby will increase the demand on your circulatory system. During pregnancy, your blood vessels will increase in size and your body will produce more blood. Your heart will work approximately 40% harder by the end of your pregnancy.
Physical changes as a result of this demand on your circulatory system include:
Feeling dizzy after standing quickly.
Changes in blood pressure.
An increased resting heart rate.
Loss of tone in your blood vessels.
It is important to be mindful of the demand put on your circulatory system during exercise. The loss of tone in your blood vessels can cause increased dizziness and lead to a loss of consciousness.
But don’t think you’re off the hook with exercise!
Evidence suggests that individuals who exercise during pregnancy have an improved blood supply to the placenta, meaning improved supply of oxygen and nutrients to their baby.
Respiratory System
The growth of your uterus can affect your ability to breath in the following ways:
Restrict the movement of your diaphragm
Limit your ability to take deep breaths
Cause shortness of breath more easily
However, you are the primary source of oxygen for your baby. Oxygen is delivered through your blood to the placenta and then to your baby. During pregnancy, the amount of air moved in and out of your lungs can increase by up to 50%. You will begin to breathe in a larger volume of air, and your rate of breathing will increase slightly.
Your Senses
TASTE
Whether you experience food cravings or aversions, most pregnant people experience a change in their sense of taste.
Preference for sweet and salty foods can increase, and you may notice an increase in your tolerance for sour foods. Some pregnant people also report a decrease or dullness in their sense of taste, but overall your sense of taste should return to normal after birth.
SMELL
Some pregnant people experience a heightened awareness and sensitivity to odors. There is little to no data to confirm this, but the vast majority of pregnant people report this change!
VISION
There is no known biological cause of vision changes in pregnancy, however most pregnant people report a change in their vision. Most common is an increase in nearsightedness, blurriness, and increased intraocular pressure. Don’t worry though, most people return to pre-pregnancy vision after they give birth.
What to Remember
Be mindful that although these changes may be difficult to adjust to, often frustrating and inconvenient, they are a sign of a progressing pregnancy. They’re also indications that your body is preparing for labour, childbirth, and to chest/breastfeed your baby.
The changes you see in your body will only last the duration of your pregnancy, and some only through your postpartum transition.
As your body shifts, so will your mind and spirit. Your pregnancy will become a time of transition, growth, and the profound beginnings of life with your child.
You’re slowly and beautifully transforming into a parent – a role in which you will forever embrace for the rest of your life.
Disclaimer: As a friendly reminder, the information provided by LILEA Parenthood is for general education purposes only and does not constitute any type of medical advice. Always consult your healthcare provider about your individual health concerns.
References:
The American College of Obstetricians and Gynecologists. “Changes During Pregnancy.” ACOG, https://www.acog.org/womens-health/infographics/changes-during-pregnancy. Accessed 25 March 2022.
Mayo Clinic Staff. “Pregnancy Week by Week”. Mayo Clinic, https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/pregnancy/art-20047208. Accessed 23 March 2022.
Planned Parenthood. “Month by Month”. Planned Parenthood, https://www.plannedparenthood.org/learn/pregnancy/pregnancy-month-by-month. Access 25 March 2022.
American Pregnancy Association. “How Your Body Changes During Pregnancy”. American Pregnancy Association, https://americanpregnancy.org/healthy-pregnancy/changes-in-your-body/body-changes-during-pregnancy/. Access 03 March 2022.
Government of Manitoba. “Making Connections: You and Your Growing Baby”. Government of Manitoba, https://www.gov.mb.ca/healthychild/healthybaby/hb_makingconnectionsA.pdf. Accessed 03 March 2022.
