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Second Trimester

The second trimester starts in week 13 and ends in week 26, and it’s a time of rapid growth for the baby. All the major structures and organs were organised in the first trimester, progesterone production has shifted from the corpus luteum to the placenta, and building on these foundations is now the primary aim.

The baby’s brain continues to develop, and the baby develops a pattern of waking and sleeping at regular intervals. The baby will notice loud noises and be able to move freely in the womb.

Baby End of 1st Trimester End of 2nd Trimester
Length 9cm (3½ inches) 27 – 36cm (11 – 14 inches)
Weight 14g (½ oz) 700g (1½ lbs)


10-week old fetus i



  • The baby now moves, sleeps, wakes, swallows and even passes urine every 45 minutes. It ‘drinks’ the amniotic fluid so that the lungs and the kidneys develop properly
  • All progesterone (the hormone of pregnancy) is now made by the placenta rather than in the ovaries
  • All of the baby’s teeth have formed, and the scalp has developed a hair pattern!
  • The baby grows to about 18cm (6.3 inches) and weighs about 85g (3 ounces)


  • She may notice a slight fluttering sensation in her lower abdomen from the baby moving but isn’t usually felt before the end of the month. Where the placenta attaches affects this a lot
  • Tiredness, occasional headaches and dizziness are still common
  • Morning sickness has usually gone by now
  • Constipation, indigestion, heartburn, flatulence or bloating may well remain, though!
  • Some new symptoms that mothers may experience include:
    • Nasal congestion
    • Occasional nosebleeds
    • Stuffiness in the ears
    • Bleeding gums and bad breath
    • An increased appetite
    • Mild swelling of the face, hands and feet
    • Varicose veins
    • A slight whitish vaginal discharge
    • Clumsiness, a lack of focus and concentration
  • Many mothers feel frustrated and self-conscious as their regular clothes don’t fit, but they’re too small for maternity clothes



  • The baby continues to grow, and all the organs are formed
  • Finger and toe prints now develop
  • The buds of the permanent teeth form beneath the baby teeth
  • Fat is stored beneath the baby’s skin, and the baby grows muscle
  • The baby sleeps and wakes at regular intervals, notices loud noises and moves
  • Fine hair called ‘lanugo’ covers the baby, and a substance called ‘vernix’ may cover the skin
  • At this point, the baby is about 25 cm (9.8 inches) and weighs up to 285g (10 ounces)


  • Energy levels are usually pretty good now
  • However, constipation, heartburn, indigestion, flatulence or bloating may persist
  • Headaches, feeling faint, dizziness, nasal congestion, nosebleeds, ear stuffiness, bleeding gums and a big appetite are common
  • Possible new symptoms are:
    • Aching in the abdomen
    • Backache
    • Swelling and cramps in the legs
    • Varicose veins
    • Haemorrhoids
    • Increased heart rate
    • Changes in the skin pigmentation of her abdomen and face


  • The hospital or midwife will schedule your anomaly ultrasound scan (usually at 20 weeks) this month



  • The baby’s brain continues to develop, and its bones become more solid
  • A special type of brown fat that keeps the baby warm at birth starts to form
  • Baby girls will develop around 3 million eggs in their ovaries during this month
  • Babies become more active as they grow larger and stronger
  • The baby’s eyebrows form, and the ‘lanugo’ gets darker
  • By the end of this month, the baby will be around 27 to 36 cm long (11 to 14 inches) and weigh about 700g (1½ lbs)


  • She’s likely to continue to have similar symptoms as the fifth month, and may also get an itchy abdomen
  • Being absent-minded, bored and anxious is expected at the end of the second trimester. Things will change


  • Resting is important, but exercise is also essential as muscle tone will be needed in a few months’ time
  • Avoid the temptation to “eat for two”; it’s not necessary, and it’s best to focus on the quality of the food
  • Many men feel left out at this point. If they’re involved in antenatal appointments, choosing names and preparing the nursery, it helps, and sex is highly unlikely to harm the baby
  • Women whose blood group is Rh-negative can could form Rh-antibodies if they’re carrying an Rh-positive baby. This is most likely to happen during birth, but occasionally it happens in late pregnancy. The complications will be for babies in subsequent pregnancies rather than this one. Giving the mother an anti-D injection after the birth reduces the problem, but an anti-D during pregnancy is sometimes recommended

i By Melchior Meijer – http://www.3dpregnancy.com/static/pregnancy-week-10.html, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=3537761
Photo by Rachel McDermott on Unsplash