Second Trimester

This guide presents a summary of each week both for you as well as for what's happening with the little one inside. So click on the week that relates to you and you can quickly see what may be relevant to you. We have tailored a summary as well as more detail information for those that want a little more detail. Wherever you see italics and or click thru you will be taken to a page with more information. At SRC we are helping women have happier and healthier pregnancies as well as helping them speed up their recovery, so they can do what matters most - is nurturing their newborn children.

  • Week 13

    Your Baby

    • Baby is now about the size of a peach
    • Heart beat now has reduced to160 bpm
    • Baby now about 70mm long

    Focus on you

    • Possible constipation because of Progesterone
    • you may start to show now
    • your breasts continue to grow


    This week you baby is approximately 70mm long and weighs about 14-20 grams.  Your baby's heart has started to slow and is now only approximately 160 bpm. Your baby moves a lot and can stretch and kick. It is able to move freely and use its muscles to push and pull itself into various positions as the connections between brain, muscle and nerves have all formed.

    The baby’s body is now growing more rapidly than its head. The fine hair (lanugo) which covers your baby protects its skin when it is floating in the amniotic fluid.

    All organs and body tissues continued to mature now.


    Welcome to the second trimester week 13-28. Your risk of miscarriage has decreased significantly, from 25% in the first weeks to 2% now.

    You may notice slight weight gain as the baby is now growing rapidly. Your uterus now fills your pelvis and future growth will mean that your uterus expands up into your abdomen. You may be looking a bit changed around the tummy, more rounded with less of a well-defined waist and a bit of a pot around your navel.

    You may still be feeling tired and lethargic but with any luck the nausea has subsided. Constipation may still be a problem because of the influence of progesterone.

    Stretch marks appear when the skin becomes over-stretched and its elasticity is decreased or lost. Stretch marks can be difficult to avoid especially if your weight gain has increased quickly. Some women get no stretch marks at all and others get a lot. The marks may appear on your abdomen, breast, hips or buttocks, and usually fade once the baby is born to thin silvery lines.

  • Week 14

    Your Baby

    • Hair (Lanugo) has started to grow all over baby
    • Reproductive organs now developing

    Focus on you

    • Linea Nigra is starting to show
    • Ears now in almost correct position
    • Oestrogen stimulates your skin cells to produce more melanin you should be able to feel your uterus now


    The baby now measures approximately 75-90mm, your weighs between 25-28 grams. Your baby’s heartbeat will be beating at around twice the rate of your own.

    Your baby's reproductive organs are developing - for boys it's the prostate gland and for girls it's the ovaries.

    The placenta has fully developed, and its large network of blood vessels is providing your baby with oxygen and nutrients. The placenta also manufactures some of the pregnancy hormones. The placenta’s primary role is to ensure that oxygen is moved into your baby’s blood stream and carbon dioxide is carried away from your baby. The waste is not limited to oxygen and also includes cleaning out other waste produced by your baby. In the same way that it ensures oxygen reaches your baby, it also plays a role in ensuring that nutrients are received. The umbilical cord is also completely mature and is made up of three entwined blood vessels. The large vein of the umbilical cord carries nourishment and oxygen rich blood to the foetus, while the two arteries are responsible for carrying waste products and carbon dioxide from the foetus to the placenta, which then processes waste. Antibodies also are passed from the mother to the foetus via the placenta. A large proportion of what the mother consumes is passed to the foetus this way, including, drugs and alcohol.

    Your baby’s eyelids are developed but the eyes remain shut. Baby’s ears have moved closer to their correct position on the side of the head. Your baby’s neck is more noticeable now. Your baby is now more human like, and structures such as chin, forehead and nose are more clearly defined. Fingers and toes are becoming fully formed. Your baby is now fully formed and will mature over the next 26 weeks.

    The sucking reflex is now developed and baby can now swallow amniotic fluid. This is then excreted as urine.


    Oestrogen is stimulating your skin cells to produce more melanin from now on. The linea alba may start to become more obvious from now on.

    Due to the increase in your circulating blood volume you may feel warm. Your heart is working very hard to supply both yours and your baby’s body with adequate oxygen. To facilitate this, your red blood cell count has increased significantly.

    You should be able to feel your uterus through your abdomen.

    Modern testing allows the early detection of abnormalities for those considered to be in a risk category. Amniocentesis can be performed between Week 14 and Week 16 to test for chromosomal abnormalities, inherited disorders, fetal maturity and neural tube defects such as spina bifida. It involves passing a hollow needle through the mother's abdomen into the amniotic sac to extract a small amount of amniotic fluid (the fluid inside the amniotic sac in which the baby floats).

    The risk of miscarriage from amniocentesis is lower than CVS testing. When an experienced doctor performs the test, the risk of miscarriage is one in 100 or lower.

  • Week 15

    Your Baby

    • Small bones in meddle ear form this week
    • Baby's legs are now longer than its arms
    • Facial muscles active
    • Head and eyebrows now grow

    Focus on you

    • Ligaments now may be affected by Relaxin
    • Shoes feeling tight- ligaments stretching
    • you may be experiencing nose bleeds


    This week your baby is about 93-104mm in length and weighs approximately 50 grams.

    The baby's skeleton is becoming stronger; cartilage is being replaced by bone. The bones will continue to remain flexible for the journey through the birth canal. Its legs are now longer than its arms.

    The three small bones in your baby’s inner ear start forming this week, so soon it will be able to hear you.

    Your baby will now be able to make a number of humorous faces - squinting, frowning and smiling as the muscles of the face are active. Eyebrow and head hair are beginning to grow.

    There is a lot of activity now and baby sleeps for long periods to recover. You will feel some of that movement soon. If this is your second pregnancy you may already be aware of that movement.


    By now you will be able to see some external signs of pregnancy.

    Progesterone and Relaxin, pregnancy hormones soften the ligaments of all your joints. This can affect pelvic function in that you may start to experience lower back pain and pelvic girdle pain. .  If the pain is more than minor discomfort you may find pain relief with SRC Pregnancy Shorts/Leggings. The ligaments of your feet also may suffer in that your feet may increase half a size or so as the foot becomes a little flatter due to ligament laxity

    Nose bleeds are common due to the lining of the nasal passage relaxing and the increase in blood circulation.

    Your breasts continue to become larger and can remain tender, heavy, and sensitive.

  • Week 16

    Your Baby

    • Hiccups are now common
    • Eyelids remain sealed
    • Can make sideways eye movements
    • Baby now moving a lot

    Focus on you

    • You may feel a flutter
    • Going to visit the toilet less as uterus now above the pelvis


    This week you baby is approximately 70mm long and weighs about 14-20 grams.  Your baby's heart has started to slow and is now only approximately 160 bpm. Your baby moves a lot and can stretch and kick. It is able to move freely and use its muscles to push and pull itself into various positions as the connections between brain, muscle and nerves have all formed.

    The baby’s body is now growing more rapidly than its head. The fine hair (lanugo) which covers your baby protects its skin when it is floating in the amniotic fluid.

    All organs and body tissues continued to mature now.


    You may start to feel the baby move from now, however it is  more common for  women who have had previous children to be aware of this early. Most women will start to feel movements between Week 16 and Week 20. You may feel the sensation as your baby moves and is usually described as a flutter. If you have not felt it yet, don't worry, you will soon.

    The top of your uterus or fundus is approximately 15cm above your pubic bone.  It is now becoming obvious that you are pregnant. Because your uterus is sitting more out of your pelvis, you will find that you need to go to the toilet less often as the pressure has lessened on your bladder.

    Constipation may still be a problem and may continue until the end of your pregnancy.

    An increase in your vaginal discharge may be irritating but this has an important protective role in the  reduction of infection risk.

    One of the most common pains during pregnancy is Round ligament pain. It most often occurs in the second trimester and can be very uncomfortable. You may feel sharp pain on the sides of your tummy. The round ligament supports the uterus and stretches during pregnancy. It connects the front portion of the uterus to the groin. Round ligament pain is considered a normal part of pregnancy as your body goes through many different changes and adjustments for your growing baby.

  • Week 17

    Your Baby

    • Organs starting to function
    • Baby weighs approx. 100 gms
    • Baby's sense of hearing is developing
    • A girls ovaries now contain all the eggs
    • A boys testicles remain in the abdomen
    • Fingerprints form

    Focus on you

    • Extra blood supply may make you feel hot
    • Aching legs
    • Brittle nails


    This week your baby is about 11-12cm in length and weighs approximately 100 grams.

    If your baby hears a loud noise it may react as its sense of hearing is developing. 

    Your baby is still very thin, with translucent skin which shows the blood vessels underneath. Fat begins to form on the foetus from this week and aids in heat production and metabolism.

    If your baby is a girl, her ovaries will contain all of the eggs she will have in her lifetime; around 3 million of them. If your baby is a boy, his testicles are still sitting up in his abdomen. 

    Your baby’s teeth have formed in their gums. Nipples are starting to become visible on your baby’s chest wall. Your baby can yawn, stretch and make funny faces. It is still sleeping a lot but will have periods where it just wants to move and exercise those muscles.

    Fingerprints are now being formed. No two persons have the same fingerprints and this is one of the truly distinctive markers which separate your little baby from anyone else’s.


    You may also be able to feel the top of your uterus half way between your pelvic bone and your belly button. The size of your uterus is a guide as to how big your baby is.

    An increased blood supply to your own body may be making you feel hot and flushed.

    Veins in your legs may be more visible and your legs are tired and aching if you stand a lot.

    Many women find their nails become brittle, frail and flaky when they are pregnant.

  • Week 18

    Your Baby

    • Baby's bones are getting stronger
    • Baby now weighs 150gms

    Focus on you

    • Top of uterus now half way between the Pubic bone and belly button
    • Your heart is working hard because your blood volume has increased


    This week your baby measures approximately 12.5-14cm in length and weighs about 150 grams.

    Your baby is looking more and more human as time goes by. Your baby can now make facial expressions, including frowning and squinting. Eyes are still closed, but are sensitive to bright light outside your abdomen. Eyelashes and eyebrows have started to grow.

    Limbs become longer, start to gain proportion and the nerves are now being coated in myelin (a fatty layer) that allows conduction of impulses.

    The lungs are developing, but oxygen will be provided by the placenta until birth.

    Your baby’s bones are getting stronger and are less like cartilage.


    Your heart is working extra hard to pump your blood. Your total circulating blood volume has increased so much that your heart needs to work almost 50 percent harder.

    You may not have gained much weight, but your uterus has been pushed forward into your abdomen and can be felt. Normal weight gain at this point is between 2.2-5.7kg.

    You will also be able to see the veins in your breasts more clearly and your nipples will be darker. A dark line (linea nigra) may be visible down the middle of your abdomen.

    You may experience episodes of low blood sugar (Hypoglycaemia) if you do not eat regularly, try and have approximately 6 small meals throughout the day to avoid this.

  • Week 19

    Your Baby

    • Eyes pointing forward
    • Ears in correct position now
    • Baby covered in a white substance called vernix
    • Tastebuds are developed
    • Baby 14 cm long, skin translucent
    • Kidneys working well

    Focus on you

    • possible indigestion
    • watch out for Urinary tract infections
    • Uterus now close to your belly button
    • Ultrasound to check baby's organ function


    Your baby is now approximately 13-15cm long and weighs about 200g.

    An ultrasound examination to check all organs is usually performed around now.

    Baby's eyes are pointing forward, rather than to the side and their ears are now in their final position.

    Your baby's taste buds have developed and its body will soon be covered in Vernix, a sebaceous gland excretion which is thick, white, and waterproof. This protects the baby’s skin and prevents dehydration.  Your baby's skin has now formed two layers - the epidermis (outer layers) and the dermis (deep skin tissue).  

    Brown fat is now being produced. This protects the internal organs for temperature fluctuations after birth.

    Your baby’s kidneys are now working well. They are producing urine which forms a fair percentage of the amniotic fluid.


    Weight gain at this point in your pregnancy should be between 2.7 and 6.3 kg.

    Heartburn or indigestion may be a problem for you due to hormones relaxing the smooth muscle of the digestive system.

    You may sometimes experience breathlessness as your heart is working very hard to supply and increased volume of blood to all your organs.

    Low blood pressure (Hypotension), anaemia, or high or low blood sugar can cause dizziness.  Get up slowly from a lying or sitting position.

    Watch out for urinary tract infections. The female urethra is relatively short and it is easy for bacteria to find their way up into the bladder.

  • Week 20

    Your Baby

    • Baby' external ears now formed
    • Baby is now approx 14-16 cm long
    • Weight now 285gms

    Focus on you

    • You may start to forget things...
    • Uterus at navel this week
    • Varicose veins may now develop


    Baby is now about 14-16cm in length and weighs in at approximately285g.

    The placenta weighs about 170g.

    Your baby’s external ears are perfectly formed. They channel sound waves towards the inner ear.

    Your baby is surrounded by around 320ml of amniotic fluid and the temperature of the fluid is a little higher that your core temperature so that your baby stays perfectly warm.

    Fingernails and toenails begin to develop more and baby’s hair continues to grow. You should be feeling your baby move during it wakeful times.  Your baby’s heart chambers and major blood vessels supplying the heart can all be seen on ultrasound this week.


    Forgetfulness is something that a lot of women experience during pregnancy. This is not only common but perfectly normal. The medical fraternity does not seem to have an answer for why this occurs.

    Your uterus is around the level of your navel this week. If you’ve had a baby before, it is possible you are showing more early than with your first. Your abdominal muscles have been stretched previously and aren’t as taut as they once were.

    You may find that you are starting to develop varicose veins, spider veins, and hemorrhoids because of hormones relaxing smooth muscle within your vessels. Some women develop varicose veins of the vulva (Vulval Varicosities). These can be very painful during pregnancy but generally resolve after delivery.

    The butterfly mask (Chloasma) affects the nose and cheeks and is a darkly pigmented facial mask and can occur in up to 60% of women. This again fades after delivery.

  • Week 21

    Your Baby

    • Weight now 310gms
    • Tooth buds starting to form

    Focus on you

    • Your belly button is now flat
    • Breast growth has stabilized
    • Nipples becoming bigger
    • Areola darker


    Baby is about 18 cm long and weighs almost 310g.

    Tooth buds are starting to form.

    Your baby has been growing quickly, but over the last week and during this week, growth slows and your baby continues to mature and gain weight.  Your baby can now swallow amniotic fluid and the water from this is absorbed through its intestine and the waste product pushed through the bowel in preparation for baby’s first bowel motion (meconium) after birth.

    As your baby’s brain develops and neural transmission develops, movements will appear less jerky.

    Tiny tooth buds for your baby’s permanent teeth are starting to form in their gums from this week. If you live in an area where the water supply is fluoridated, your baby will be getting the benefits. The placenta will do a good job filtering out many substances, though fluoride is one of the compounds which are transferred through the placenta.


    Usual weight gain up to and including this week is between 3.6 and 6.3 kg.

    Many women find their belly button is flat and at the same level as their surrounding skin. As the baby grows your belly button may well pop out.

    Breast growth has probably stabilised. Your nipples will become bigger and the areola will darken as your pregnancy advances.

    Your baby is now laying down fat stores so you will notice the increase in your weight.

  • Week 22

    Your Baby

    • Baby's skin is now opaque
    • Sweat glands developing
    • Testes descending into scrotum this week
    • Testosterone already active!

    Focus on you

    • Fluid retention
    • Lower back ache
    • Breathless
    • Constipation


    Baby is now 19cm long and weighs 350g.

    Eyelids, eyebrows and fingernails are developed. Organs are maturing so that they can perform their particular functions.  Baby teeth have been formed and are waiting in the gums. Your baby can now taste and can tell the difference between sweet and bitter.

    As a natural defense against infection an immune system is forming. The “brown fat” continues to build up and will continue to do so until your baby is born. Your baby's skin, no longer transparent, is now milky looking, and sweat glands are developing. For girls, the vagina, uterus and ovaries have formed and for boys, the testes will be dropping into the scrotum this week, with testosterone and juvenile sperm already active.


    You may start to retain some fluid in your legs and ankles and this is usually at its worst towards the end of the day. Venous return has slowed and sometimes the veins become leaky hence the fluid retention in the extremities.

    Progesterone and Relaxin continue to soften the ligaments of the entire body but the effects of this is usually felt most in the lower back and pelvic girdle, potentially causing pain in those areas. Conditions that arise for this are Lower back painSymphysis Pubis Dysfunction and Sacro Iliac Joint (SIJ) pain and dislocation. . If the pain is more than minor discomfort you may find pain relief with SRC Pregnancy Shorts/Leggings.

    Your lung capacity may be affected and you may feel breathless as your uterus grows up past your navel within the next weeks. Your ribcage will move up and out a little to accommodate the increasing uterus within the abdominal cavity.

    Indigestion, heartburn and constipation may still be a problem!

    Abdominal muscles stretching and subsequent separation can occur as your baby grows. The degree of muscle separation will depend on the size of your baby and potentially how tight your muscles were to start with. The tighter the abdominal muscles pre pregnancy the greater the risk of separation as they do not relax as easily.  As your abdomen stretches, your skin also stretches causing it to feel itchy.

  • Week 23

    Your Baby

    • Baby now weighs 500gms
    • Surfactant now being produced
    • Baby's ears now fully functional
    • Able to react to loud noises
    • Skin a little saggy

    Focus on you

    • Muscle Cramping at night
    • Increased vaginal discharge
    • Braxton Hicks contractions


    Baby is roughly 20cm in length and weighs 500g.

    Your baby's body and face start to look like the appearance of a newborn baby. Its skin is still a little saggy right now because its skin grows faster than the fat that is being deposited underneath it.

    The pancreas develops more this week, allowing the production of insulin, which metabolises sugars.

    Surfactant which helps the alveoli stay open after birth is being produced in the lungs.

    Your baby can hear and its ears are fully functioning and will jump or kick if there is a sudden loud noise. Baby’s movements are becoming more and more coordinated as the weeks go by.

    The long bones now have marrow and assist  the creation of blood cells.


    Because of some fluid retention, vasodilation and weight gain your face may appear fuller and have what is described as a “glow”. Carpal Tunnel Syndrome can also occur due to fluid retention. This causes “pins and needles” of the hands due to the radial and ulna nerves being compressed by the surrounding fluid.

    Uterine contractions known as Braxton Hicks are common now and are generally concentrated at the top of the uterus. These harmless and usually painless contractions are just your uterus practising for delivery.

    Your vaginal discharge is likely to have increased. During pregnancy this is normally clear to white in colour and odourless.  Wearing a liner through the day can be helpful but it may increase the risk of developing a yeast infection.

  • Week 24

    Your Baby

    • Baby now weighs 570-680gms
    • Eyelashes and eyebrows grow this week
    • Baby now approx 30cm long

    Focus on you

    • nipples darker and more prominent
    • Stretch marks may start to form
    • Headaches common
    • Glucose tolerance test


    Your baby is now 21cm and weighs 570- 680grams. It is forming footprints and fingerprints, individual markers which will reflect its own DNA as different from anyone else’s.

    Your baby continues to gain weight. Further development is taking place in the brain, kidneys, lungs and gastrointestinal tract. Baby can now open its eyes and its eyelashes and eyebrows grow this week.


    Your healthcare provider will send you for glucose tolerance test during week 24-28. This test screens for gestational diabetes which, if left untreated, can cause low blood sugar issues in your newborn baby.

    Your baby’s movements become stronger and more pronounced. They are a good sign that the baby is healthy.

    During pregnancy your nipples generally become darker and more prominent.  In addition you may develop small pimples on your areolas called Montgomery’s Tubercles. They secrete an oily lubricant which will help to nourish your nipples and keep them supple.

    As your tummy grows and the skin stretches you may notice stretch marks forming. They occur when the collagen fibres in the middle layer of skin (the dermis) stretch and tear.

    Headaches are common throughout pregnancy and could be related to not drinking enough water or having a low blood sugar level from not eating often enough.

    Your baby’s nostrils are now open. Previously they were closed over. Surfactant is constantly being produced; this continues to coat the alveoli so that they remain open after birth.

  • Week 25

    Your Baby

    • Weigh 720gms
    • Hiccups regularly
    • Stretching common
    • Baby's adult teeth are now formed

    Focus on you

    • Heartburn & Indigestion common
    • Gum swelling and bleeding
    • Pelvic and back pain increasing


    Your baby is now about 22cm and weighs approximately 720 grams.

    Growth is steady and hiccupping and stretching is common, along with rest periods when the baby will be quite still in comparison. Adult teeth have formed by now in the jaw bone.


    Your organs and intestines are feeling the pressure of the confined space because of your ever enlarging uterus. As a result you may have episodes of indigestion and heartburn from this point on. You can also try sleeping propped up on a couple of pillows.

    Gum swelling or gingivitis is also common and you may notice some blood on your toothbrush.

    The ligaments and muscles supporting your expanding uterus are under stress as Progesterone and Relaxin; pregnancy hormones are loosening and stretching the firm fibres. This prepares your body for childbirth. Pain associated with the loosening of the ligaments (Pelvic Girdle Pain) of the pelvis and back (Lower back Pain) can be very uncomfortable.  If the pain is more than minor discomfort you may find pain relief with SRC Pregnancy Shorts/Leggings.

  • Week 26

    Your Baby

    • Baby weighs 900gms
    • Eyes now starting to open
    • Lots of movement now
    • Top of Uterus now between your belly button and ribs
    • Heart beat around 150 bpm

    Focus on you

    • Total blood volume increased by 25%
    • More Braxton Hicks contractions now
    • Constipation very common
    • Postural hypotension


    Baby’s length is around 23 cm and weighs nearly 900grams. Heart rate is around 150 bpm.

    Its head is now growing more slowly than its body. The bones of the arms and legs are getting stronger every day. Eyebrows and eyelashes are present and hair on the head is growing longer. Your baby is becoming longer, and although still red and skinny, fat deposits continue to be laid down under the skin. Genitals are now completely differentiated.

    Your baby can now open and close its eyes and will continue to blink and practice focusing until birth.

    Lots of baby movements from now until your 30th week.  Amniotic fluid isn’t being created in the same volumes as it was a couple of weeks ago. You may be more aware of baby’s movements because of this.


    The top of your uterus is now about two finger widths above your belly button, and you may begin to find that sleeping/lying down is not that comfortable.

    As your tummy grows you may begin to feel a little awkward as your center of gravity has changed.

    Your total blood volume has increased by around 25% since the start of your pregnancy; it won’t peak until closer to 35 weeks. All that extra circulating blood and dilated vessels to keep you cool will mean you may notice your fingers and ankles swelling by the end of the day. In addition a sudden drop in blood pressure (postural hypotension) can occur when you get up quickly from lying to sitting of from sitting to standing.

    Braxton Hicks contractions are making your uterus contract at irregular intervals in preparation for the impending birth.

    Constipation may remain an issue.

  • Week 27

    Your Baby

    • Weighs now 1kg approx
    • Average length is 24cm
    • Subcutaneous fat is forming

    Focus on you

    • Ribs expanding out
    • Retina now developing
    • Fluid retention may cause Carpal Tunnel abdominal muscles stretching
    • Skin stretching


    Baby’s length is now 24cm (head to rump) and weight is approximately 1 kg. It can be measured from its head to its heels from this week on as it is spending less time curled up. On average, head to toe length at 27 weeks gestation is 34- 37 centimetres.

    Your baby is growing quickly and your baby’s skin is less wrinkly now as more subcutaneous fat forms.

    Around this time the retina develops. It is situated at the back of the eye; it receives information and communicates that information to the brain where it is interpreted.

    Your baby has learnt how to pacify itself and can now suck its thumb when it desires. It is still breathing the amniotic fluid in and out of its lungs, practicing for those all-important first breaths when it is born. All of your baby’s oxygen needs are still being supplied by the placenta. Antibodies from you to baby are also being transferred via the placenta.

    Your baby has been able to hear since about Week 20 but loud, sudden, or unanticipated noises may still cause your baby to jump or kick.


    Antenatal (pregnancy and birth) classes are available to all pregnant women and their partners. They are not compulsory but very beneficial, especially for first time parents. The classes cover a range of useful topics associated with your pregnancy and birth. 

    As your uterus is expanding up and out, your rib cage is also moving out to accommodate the growth. Breathlessness is common as your lungs may be feeling a little squashed and you are responsible for providing adequate oxygen through the placenta to your baby and also oxygen for your own survival.

    Abdominal muscles continue to stretch and the fascia between Rectus Abdominus muscle can stretch and tear causing Diastasis of Rectus Abdominus Muscle or DRAM.

    The skin on you tummy may feel itchy constantly as it is stretching to accommodate your growing uterus.

    Fluid retention can cause Carpal Tunnel Syndrome. This occurs when fluid around the wrist causes pressure on the ulna nerve in particular. This will resolve after you have had your baby.