What can dads expect in the Second Trimester of Pregnancy?

Right, so 12 weeks have passed and things are happening. For mum-to-be, it’s generally a time to rejoice, although that may depend where she is today on the scale from blissfully-Instagram-pregnant-glow to “You did this to me, I hate you and also bring me some chocolate and then die”. To be honest it’s a bit of a lottery.

For most women, their second trimester comes as a welcome relief. The exhaustion and nausea which has been so consuming in the first often seems to settle and there is almost a return to their normal state of well-being. Internally, your forthcoming sprog is kicking goals, or at least, developing the legs to kick them—and your partner’s surrounding organs— as delivery day beckons. The next three months will see your future child increase in size 3-4 times, look like an actual humanoid, and continue to develop essential organs and body systems, all of which are now in place.

Strap yourself in.

Has anyone seen my waist?

Mum may find it is getting harder to hide the reality of her pregnancy at this stage. When women start to ‘show’ is highly individual and depends on their overall size and stature, if they've had children previously, how accurately they have estimated their dates, and even the tone of their abdominal muscles. At the start of the second trimester, the uterus is just starting to rise up from the central pubic bone. Until then, it has been protected within her pelvis but now becomes too large to accommodate and needs to lift up and out.

Your partner may worry if she still can’t feel anything when she’s poking around on her tummy, but you can calm her nerves. At this early stage of her pregnancy, in the second trimester, how big she is outwardly is not an indication of your baby's growth or wellbeing.

Her physical changes in the second trimester

• There’s a chance that her nose has been running for some time now. That sniffle, which has been irritating both you and her, is likely to hang around for a few more weeks. You can suggest limiting the amount of time spent in low humidity environments and air conditioning, and a bowl of water or humidifier in the room can help make breathing easier, but ultimately, she’ll have to ride this one out.
• Her size and shape are going to change in the next few months, and while you’ll both have been expecting this, it will still be a novelty. Every woman carries differently. Lots of people will tell you it is possible to determine the sex of your baby from how much an expectant mother’s tummy sticks out, although these are often the same sort of people who know the star sign for their cat. There is no scientific proof to support this theory, there is no harm in having a little fun.
• She can get ready to feel Braxton Hicks Contractions from around week 26. These are painless uterine contractions which are designed to prepare her uterus for labour and increase its blood flow. She may be conscious of them earlier if she’s given birth before.

Her emotional changes in the second trimester

• Hormones can be responsible for lots of pregnancy mood changes. So be prepared. One of the more common symptoms heralding the start of the second trimester is pregnancy amnesia. In other words, she’s not losing her marbles, she’s just losing her handbag, and her keys, and her phone. Make things easier for her by encouraging her not to do too much at once, and have a laugh together at any symptoms. A sense of humour often helps.
• In the wee small hours and quieter moments, she might find herself worrying if the baby will be alright and how she will cope if it isn’t. There is often a sense in the second trimester that there is no going back. There are no guarantees or ironclad contracts when it comes to baby making, but be reassured, nature is very clever and gets it right most of the time. You’ve got this, and you’ll get there together… even if nature dictates that she is stuck doing most of the work, at least for now.

Hints for the second trimester

• Get used to the idea of attending regular ante-natal appointments with her. Routine checks and when recommended, ultrasounds, help to screen for potential problems. It is common for pregnant women to have a range of checks at each visit. This is usually every 4 weeks or so throughout the second trimester. It’s best if you both go to every appointment, if possible.
• Think about what you’re eating. She doesn’t need to eat for two, just really well for one—but it can be a lot easier with a partner’s encouragement. She’ll need lots of carbohydrates and protein, iron and calcium in her diet; remember, everything that goes in will eventually find its way through to your baby and will help them grow. Note that around half of all expectant fathers gain weight during their partner’s pregnancy—up to 14kg, according to an American study. Be careful.

Mum-to-be will properly start gaining weight through her second trimester. Most women find their weight remains stable in the first trimester or even drops in response to their appetite changes. Don’t stress too much if she is gaining weight. A healthy pregnancy weight gain is based on pre-pregnancy weight and the Body Mass Index. You can read more on healthy pregnancy weight.

Note that gaining more than that the healthy amount can cause pregnancy and labour complications.

Detailed week-by-week changes in the second trimester

14 weeks Pregnant

Your baby is the size of your clenched fist… or mum’s, anyway. Its eyelids are fully formed but are still fused over its eyes, which is the way they’ll stay throughout the second trimester.

15 Weeks Pregnant

This week your baby can swallow, and it will soon begin gulping down the amniotic fluid in which it’s floating and recycling it through its kidneys. It’s a disgusting miracle of creation! If this sounds less than tasty, remember that this is one way of determining if a baby has kidney problems and helps their lungs to mature.

16 Weeks Pregnant

Baby is almost 13 centimetres long this week. It is moving quite actively now and has alternating periods of rest and activity, like a wedding reception dancefloor that only fills for the bangers. All that movement helps your baby's muscles to grow and consolidate the network of nervous system pathways linking their brain, spinal cord and muscles.

17 Weeks Pregnant

Your baby's trunk will begin to straighten out and its legs are getting longer. This week your baby has eyebrows and eye lashes, to match its hairy little Teen Wolf body. Don t worry though, unless your baby comes early, all that fuzz, known officially as lanugo, will be lost.

18 Weeks Pregnant

If this is her first pregnancy, she will probably be aware of baby's movements by now. If she’s been pregnant before, it is possible to feel movements or quickening from around 14 weeks.

19 Weeks Pregnant

This week your little one is the size of a mango, only less delicious (probably). In another piece of evidence that pregnancy is weird, a white oily coating known as vernix caseosa is forming on its skin around now; another means of protecting that tender dermis.

20 Weeks Pregnant

Your baby is around 21 centimetres long. It is possible to see what sex your baby is on ultrasound now, if not for the past couple of weeks. Her uterus is at the half way mark and will now reach up to her navel.

21 Weeks Pregnant

Baby is the length of a banana this week. Its arms and legs look as if they are in proportion with each other and those kicks she is feeling are less random and sudden. They seem to be stronger and more intentional than they have been, and—prepare for tears—you’ll probably be able to feel them, too, if you haven’t done so slightly earlier.

22 Weeks Pregnant

Baby is hearing a lot of muffled noises by now so mum can get into the habit of talking to it, playing music and even you chat away to it through her tummy wall. This will pay off when the baby is born and it responds to your voices.

23 Weeks Pregnant

Go time. In the next month, baby will double its weight. They will fill out to fit their skin and lay down all important fat. You’ll probably notice mum is getting properly bigger by now.

24 Weeks Pregnant

Baby is around 22 centimetres long. The amniotic fluid is being sucked in and out of its lungs in a breathing motion. Lots of energy is going into baby growth, with fat deposits being laid down. There's also hair forming in all the mandated places, especially eyebrows, eyelashes and on their head.

25 Weeks Pregnant

Air sacs are forming in baby's lungs, in preparation for their first breaths. There's lots of lung development happening this week and although you are still doing all the breathing for your baby at the moment, they’ll need to be ready to breathe on their own from the moment of birth.

26 Weeks Pregnant

Your baby's eyes may actually be able to see! You may find they are more active when mum is out in direct sunlight, and they are able to respond to touch through the abdominal wall, and will move in response to gentle pressure on her tummy wall. Baby is roughly the same size as the placenta this week.

27 Weeks Pregnant

Her insides are a one-kid moshpit this week, with lots of movements and activity, and regular bursts of kicking and stretching. Baby is still practicing breathing, though if they were born this week, they would most certainly need help to breathe. Watch and feel for her tummy jumping rhythmically when mum gives you the word—it could be that baby is hiccoughing.

Edited by Ben Smithurst. Jan 2023. Ben is a father of two, dad blogger, and journalist from Sydney. You can find more of his work at directadvicefordads.com.au.

Reviewed by Jane Barry, midwife and child health nurse on 10/02/2023