Week 13 of pregnancy (Days 91-97)

This week marks the end of the first trimester, and the risk of miscarrage reduces dramatically. Many women notice the start of a "bump" around this time.

Trimester Chart
A Guide to each week of your pregnancy, with details on your baby’s growth, your body and symptoms to look out for.
  • 4

    Your baby is no longer a zygote or a single cell. The cells have multiplied rapidly and now the embryo is taking shape.

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  • 9

    From week 9 you can have Non-Invasive Prenatal Screening, to assess your risk of Down's Syndrome and other conditions.

    How many weeks pregnant?

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  • 13

    This week marks the end of the first trimester, and the risk of miscarrage reduces dramatically.

    How many weeks pregnant?

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1st Trimester

 

 

 
  • 14

    Your baby now measures around 8cm, from crown to rump and weighs around 40g.

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  • 22

    Your growing baby now measures 28cm from crown to heel and weighs approximately 350g.

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  • 28

    Your growing baby now measures 38cm from crown to heel and weighs approximately 1kg.

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2nd Trimester

 

 

 
  • 29

    Your growing baby now measures 39cm from crown to heel and weighs approximately 1.1kg.

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  • 36

    Your growing baby now measures up to 47.5cm from crown to heel and weighs approximately 2.7kg.

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  • 40

    Your baby is now considered full term and will not normally gain much weight at this point.

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3rd Trimester

 

 

 

Ultrasound image of fetus at 13 weeks gestation.

You should give yourself a pat on the back as by the end of this week you will have completed your first trimester. Many women find the first trimester the most difficult due to the anxiety over threatened miscarriage and the nausea. As your pregnancy progresses you will find that you’ll have to adjust to the weight gain and extra strains on your body but many women report surges in energy during the second trimester.

Your Baby

Your baby now measures between 6.4cm and 7.6cm from crown to rump (or head to bum) and weighs approximately 14.2g to 21.3g. At thirteen weeks, your baby’s bones are beginning to form in the arms and legs and the intestines are beginning to spread from to the umbilical cord to the abdomen. The vocal cords are also developing at this stage. The amount of amniotic fluid increases to around 100ml.

Your baby is developing what looks like a personality on a scan as she or he has the reflexes to suck and root. The movement in the arms and legs is now more refined, making it possible for the fetus to put its hand in its mouth. Many babies on scans at this stage can often be seen sucking their thumb. The muscles in the neck are now sufficiently developed for the head to move freely from side to side and up and down

If the fetus is a girl, the ovaries will now contain approximately 2 million ova, (eggs). This number will decrease to 1 million by birth.

Your Body and Symptoms

If you do have the energy surge that some women experience, take advantage of it to do some gentle exercise. This will release endorphins that will lift your mood while helping you sleep soundly. This is a good habit to get into as in the later stages of pregnancy you may find it difficult to get comfortable in bed while common ailments such as indigestion and heartburn, or frequent urination may interrupt a good night’s sleep. Your rest is highly important.

Your midwife or doctor will be able to advise on the best types of exercise along with some you may need to avoid. Although your energy levels may be higher than usual it’s important that you don’t overdo it. Stick to low impact exercise only.

You may still be, or start to experience a change in your vaginal discharge. This thin, milky discharge is known as leukorrhea and is completely normal. Its function is to help maintain a healthy balance of bacteria in the birth canal and reduce the risk of infection.

You may also notice that veins are more prominent and noticeable all over your body. This is simply because the veins are now transporting an increased blood flow around your body to carry the additional nutrients needed to support the placenta and foetus. These veins will fade after you’ve given birth.

By this stage, you are likely to be noticing a change in your body shape, with your tummy becoming noticeably more rounded. Your midwife will now be able to easily feel the top of your uterus, as it is now large enough to rise above the level of your pelvis. If you feel that you are gaining too much weight too quickly, it could be that your due date has been miscalculated (this will be corrected during your scan if you have not already had one). Alternatively, you abdomen may be distended due to bloating. Your midwife or doctor will be able to investigate this further if you have any concerns.

Symptoms to Watch Out For

Vaginal bleeding is not uncommon. When it is not paired with menstrual cramps, it’s usually harmless although medical professionals will call it a threatened miscarriage. Bleeding may continue for some days but generally changes from bright red to dark red to brown before it disappears. In some cases a bruise is seen on the placenta on ultrasound scan: this is called a subchorionic haematoma. The dark red bleeding is likely to be persistent if this is present. If you have any concerns at all, call your midwife or call in to see your Doctor.

Your Care on the NHS

By now you should have had your booking appointment along with your “dating scan”. The ultrasound would have given you a more precise age of your baby. You’ll now have a definite due date although few babies are actually born on this day. If this is your first pregnancy it’s perfectly normal for your baby to be delayed by up to two weeks.

You may have already taken the combined test to determine the chances of chromosome disorders such as Down’s syndrome. Your results may not be back just yet but if they do show a high possibility with the ratios the NHS use, you may be offered a CVS or amniocentesis test. See our website for more details on this as it can provide some risk however there is an alternative that is completely safe.

If your GP has sent a letter to the local hospital/midwife then you may have an appointment to see her at this stage. She will have a long talk with you about pregnancy and birth. She will take some blood samples that are routine in pregnancy and may also take the blood sample used for the Combined Test for Down's syndrome. By this stage an ultrasound scan should have been scheduled. This is the 12 week scan or nuchal translucency scan. This is the routine combined test for screening for fetal abnormalities. The nuchal fold, the back the the neck of the fetus, is measured and a blood test is taken for two pregnancy hormones. A risk estimate for Down’s syndrome is then calculated. The result may take a few days because most hospitals send the blood off to an outside laboratory. This scan will also check the fetus generally for abnormalities. The following structures will be checked: head spine, body, stomach, bladder legs, arms, hands and feet. It is important to note that abnormalities of the heart, kidneys and face will not be obvious at this stage.

Private Care Available

In a private clinic you can have a full consultation whether you have particular concerns or not. You can have the nuchal translucency scan (12 week scan) with a blood sample (the combined test) similar to the NHS one and if desired you can have the Harmony or Panorama test. This is particularly relevant if you are over 35 years or have had a previous abnormal pregnancy.

If you are still experiencing heartburn or indigestion you can talk to a nutritionist who will help you identify the trigger foods to avoid for relief.

You can also book a scan privately at any time during your pregnancy to see how your baby is growing. Some mothers like to see their baby on the screen every few weeks!

Scans and Packages

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