Sunday, July 14, 2024

The Middle: Weeks 12 to 28

This is an INFORMATION page, verified by physician

By now as you are leading into the second trimester, you should have had your first scan to look at your baby’s head, spine and arms and legs. The measurements taken during this scan should confirm your expected date of delivery. Remember that only 5 in 100 babies put in an appearance on their actual due date. A small number of babies make an early appearance, so try not to leave all your preparation to the last minute.


The first trimester of pregnancy is often a time of feeling really fatigued. You may also feel nauseated and sometimes women can experience vomiting. By 12 weeks of pregnancy and leading into the second trimester, those symptoms should be easing off and you may be starting to really bloom with all the pregnancy hormones. Sadly, for a small number of women, the sickness doesn’t pass. If this is affecting you please discuss this with your obstetrician. This is important to make sure you are getting enough nutrition for you and your baby.

There is no need to eat for two. You only need a very small increase of calories to support your developing pregnancy


Some women do continue to feel tired. It’s important to check your blood results to make sure you aren’t anaemic and need iron supplements. Don’t feel bad if you still need a rest during the day. Remember that being pregnant is often exhausting. For many women, it’s equivalent to doing an office job, on top of your commitments to work and family. Be kind to yourself and listen to what your body is telling you. If you need rest, take it.

Baby’s development

As you are now in the second trimester, the baby’s organs will now have completely formed. The rest of your pregnancy is all about the baby’s growth and brain development. It is safe to resume or continue gentle exercise at this stage of pregnancy. Vigorous exercise should be discouraged. You need to be aware that your ligaments will have softened due to pregnancy hormones. Take extra care, particularly of your back when lifting, bending and exercising.


At 18-20 weeks you will have your detailed anatomy scan. This scan is checking that the baby’s important organs have developed as normal. Usually this scan can tell you whether you are having a boy or a girl. If this scan shows any concerns you may need further scans during the pregnancy. Occasionally, women may need referral to a specialist for a more detailed assessment of their baby.

The vast majority of babies are born completely normal. But it is important to remember that some problems cannot be detected before birth. This is why the checks by the paediatrician are so important at birth and beyond.

Monitoring Pre-eclampsia

You will continue to see your obstetrician every 4 weeks. They will be checking your baby’s growth and your wellbeing. These checkups include monitoring your blood pressure and urine testing. They are screening you for pre-eclampsia which is a blood pressure complication of pregnancy. It doesn’t cause symptoms until the very late stages of pregnancy. It’s important to have these regular blood pressure and urine checks so make sure you aren’t quietly developing a problem.

Gestational Diabetes

Another common problem is developing diabetes in pregnancy (gestational diabetes – GDM). There are risk factors which can identify women at an increased risk. This includes a strong family history of diabetes or women who are carrying extra weight. But some women with no risk factors can also develop GDM. For this reason, it is recommended that all women are screened at 27-28 weeks of pregnancy for GDM.

You will be invited to have a glucose tolerance test at around 27 to 28 weeks of pregnancy. This test checks your fasting blood glucose level, so you can’t eat or drink anything (apart from water) from midnight the night before the test. After the first blood test you will be given a very sugary drink. Then you will have another blood test later to check how your body handles this glucose challenge. If you are diagnosed with GDM you may be given specific dietary advice, referred to a dietician or may need to start on tablet or injection medication. Your obstetrician will support you with this.

Rhesus Negative

Around 1 in 7 women have a blood type called Rhesus negative. They are at risk of developing antibodies if their baby has the blood group Rhesus positive. These antibodies can cross the placenta and cause the baby to become anaemic. This means that the baby doesn’t get enough oxygen from their bloodstream.

To prevent women with Rhesus negative blood group from developing these antibodies, it is recommended that these women have an injection of Anti D antibodies at 28 and 32 weeks of pregnancy. All women should have a blood test to check their blood group antibodies at this stage as a very small number of pregnancies can develop ABO antibodies. This is important information for your paediatrician to know at the time of delivery.


All mothers pass important antibodies across the placenta so that their babies are born with immunity to some serious infections. This usually lasts until their own immune system starts working properly around 3 months of age. For this reason, it is recommended that pregnant women have vaccinations. This enables antibodies to cross the placenta and protect their newborn baby. It is known that these vaccinations are safe in pregnancy. They significantly reduce the risk to the new born baby. You will be offered the whooping cough (pertussis) vaccine called Tdap. You should continue to have your annual flu vaccination in the autumn before the start of the peak flu season (December to January).

You will meet your obstetrician at 28 weeks of pregnancy. In this meeting they will assess your baby’s growth and plan for your third trimester of pregnancy. A growth scan may be recommended at this stage. Especially if your baby bump seems to be bigger or smaller than expected or if you have developed any pregnancy complications. This also gives you the chance to ask any questions about your pregnancy progress and start to plan your delivery.

More Advice on The Second Trimester

It’s also worth checking out help, advice, and any on the second triemster posts in our Baby Facebook Group. It allows you to ask questions, gain access to basic advice and share experiences with others facing the same new experiences. You can join here:

about the author

Dr Lisa Joels
Dr Lisa Joels
OBSTETRICIAN & GYNAECOLOGIST - Dr Lisa Joels (MB ChB, MD, FRCOG, FHEA) has 34 years’ experience in obstetrics and gynaecology including 19 years as a Consultant working in Swansea (2001-11) and subsequently at the Royal Devon & Exeter NHS Foundations Trust in the UK (2011-20). These are both University teaching hospitals, each having more than 4,000 deliveries a year and providing tertiary obstetric and neonatal services as well as gynaecological services to their local population. Dr Joels has experience in management of complex obstetric and gynaecological problems including a multi-disciplinary approach and working closely with related specialties such as midwifery, neonatology, paediatrics and anaesthetics. She believes in a woman-centred holistic approach to clinical management and is an advocate for patient choice and shared decision making.
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