Pregnancy 1st Trimester

Pregnancy- First Trimester week by week

These pages will take you through your first trimester of pregnancy week by week.

Pregnancy typically lasts for 40 weeks from the first day of a woman’s last menstrual period.

The duration of the pregnancy is divided into stages known as trimesters, each lasting about 3 months.

During this time a woman’s body undergoes many changes to support the growing fetus and prepare for childbirth.

First trimester:  0-13 weeks

Second trimester:  14-27 weeks

Third trimester:   28-40 weeks

First Trimester of pregnancy

During the first trimester of your pregnancy your body is working hard to adjust to being pregnant. At the beginning of the first trimester you will not look pregnant and you may not even feel pregnant, but very soon your hormones will begin to affect you in many different ways, you may start to suffer mood swings, nausea and fatigue to name a few. Now is the time to start taking care of yourself and making sure you eat a healthy nutritious diet including plenty of fresh fruit and vegetables, ensuring you drink plenty of water a day is also extremely important- try to drink at least 8 glasses a day. Getting adequate rest will be of great benefit to your wellbeing as extreme fatigue can easily strike during the first trimester. Drugs, smoking, caffeine, junk food and alcohol should be avoided throughout your whole pregnancy.

If you need advice and support to help you stop :

Taking Drugs, call the National Drugs Helpline on 0800 77 66 00 (24hrs a day) or log on to www.talktofrank.com

Drinking alcohol, call Drinkline on 0800 917 8282 (mon-fri, 9am-11pm) or log on to www.wrecked.co.uk

Smoking, call NHS pregnancy smoking helpline on 0800 169 9 169 (12noon-9pm) for extra support visit www.givingupsmoking.co.uk

First trimester screening for Down’s syndrome involves an ultrasound test to check for excess fluid behind the fetal neck (nuchal fold thickness).This scan is also used to confirm the age of your baby and confirm expected delivery date. A blood test is also sometimes used to screen for Down’s syndrome- Blood is tested for high levels of plasma protein A and hCG, these two hormones are produced by the fetus and passed into the mother’s bloodstream. Women whose results are abnormal would be offered amniocentesis.

Weeks 1-4 of Pregnancy-First Trimester

Most women are not yet aware that they are pregnant at this stage of their pregnancy.

Your baby begins as a single cell which is formed when the egg and sperm join, this is known as the moment of conception. This then implants itself in the lining of your uterus and begins to produce pregnancy hormones. Your baby is growing faster now than at any other time during your pregnancy.

At the moment the egg and sperm join the sex of your baby is decided. The egg always contains an X chromosome whereas a sperm can carry either an X or a Y. If the sperm is carrying another X chromosome your baby will be a girl and if the sperm is carrying a Y chromosome your baby will be a boy.

For the signs and symptoms of early pregnancy please see the early signs of pregnancy page, you may also find our page on Home pregnancy tests of some interest to you.

Pregnancy Week by Week

Your first trimester of pregnancy week by week page 2

Week 5 of Pregnancy-First Trimester

You could be feeling pregnant now and could be suffering from one or all of the early signs of pregnancy symptoms which are very common during the first trimester of pregnancy. Your baby is about 2mm long, which is the size of an apple seed. Your baby has begun to form a heart which will begin to beat soon and the neural tube is developing which will form your baby’s brain, spine and nerves.

Medicines

It is very important not to take any drugs or medicines unless they have been prescribed by your doctor who is aware you are pregnant. This also applies to medicines you can buy for headaches, colds, sore throats and hay fever. Aspirin and ibuprofen should be avoided as they can encourage bleeding.

Caffeine

High levels of caffeine can cause low birth weight or even miscarriage so it is extremely important not to have more than 300mg of caffeine a day. Cup of instant coffee (75mg), 50g bar of chocolate (50mg), Cup of tea (50mg), Can of cola (40mg), these figures are only a rough guide check individual products carefully.

Folic acid

If you are not already taking a folic acid supplement now is the time to start. Folic acid which is one of the B vitamins will help your baby’s spine to develop properly. Even before most women know they are pregnant the baby’s brain and spine have begun to form. The baby’s spine develops from a part of the embryo called the ‘neural tube’. If the spine does not develop properly babies are born with ‘neural tube defects’ such as spina bifida (split spine). Children with spina bifida may be unable to walk or look after themselves.

You should take a folic acid supplement containing 400 micrograms (400 mcg) daily from when you start trying for a baby and until you are 12 weeks into your pregnancy. Please check with your doctor or pharmacist if you are unsure of which supplement to choose.

To boost your levels of folic acid further try to include foods rich in folic acid in your daily diet: Dark green leafy vegetables such as Brussel sprouts, spinach or spring greens, take extra care not to overcook the vegetables as this destroys the folic acid. Citrus fruits eg oranges and tangerines. Black-eyed beans, broccoli, green beans, cauliflower, peas and nuts. Many bread and breakfast cereals often have added folic acid- check the label.

Foods Which You Should Avoid

• Soft, mould ripened, blue-veined, or unpasteurised cheese such as Brie and Camembert, Stilton or Danish Blue. These could contain listeria or bacteria.
• Unpasteurised milk, either from goats or cows. These could also contain listeria.
• Liver and all products containing liver as these could contain large amounts of Vitamin A. Vitamin A in large doses has been linked to birth defects. Pates also could contain listeria.
• Soft-boiled eggs and raw eggs and products made from raw eggs, such as home made mayonnaise. Also avoid soft whipped ice cream from kiosks. All these products could contain salmonella bacteria.
• Raw or undercooked meat, fish or chicken. Undercooked meats can also contain the salmonella bacteria. Avoid fish containing high levels of mercury such as, swordfish, marlin, shark and limit tuna to no more than 4 medium cans or 2 fresh tuna steaks per week.
• Unwashed salads and vegetables. These could contain the listeria bacteria or the toxoplasmosis parasite.
• Any foods that may have not been cooked through properly such as pre-cooked foods eg. chicken drumsticks. They could contain listeria.

Week Six of Pregnancy-First Trimester

Your baby is about the size of a pea and is beginning to develop tiny buds that will become their arms and legs. Your baby has all the vital organs in place, heart, kidneys, and liver but obviously these organs need much further development. Your baby’s heart is now the size of a poppy-seed.

Week Seven of Pregnancy-First Trimester

At this stage of your pregnancy your baby is about the size of a bean and is growing surrounded by fluid, the brain, bones and muscles are continuing to grow. Your baby also has a tiny tail, but this will disappear!! You will not be able to feel your baby move yet but they make their first movement this week.

Week Eight of Pregnancy-First Trimester

Your baby now measures about 2 cm and has fingers and toes and his or her bones in the face are beginning to form. Your baby’s skin is paper-thin. He or she is floating in a pool of protective liquid known as amniotic fluid.

Week Nine of Pregnancy-First Trimester

By week 9 you may be noticing that your waistband is beginning to expand, start thinking about buying some comfortable clothes, tight clothes around your waist can make nausea, heartburn and indigestion worse. Your baby now measures around 2.5cm and his or hers fingers are getting longer and also has eyelids and developing ears. Some of your baby’s organs, nerves and muscles are beginning to work.

Week Ten of Pregnancy-First Trimester

You may be noticing that your nausea is beginning to fade although you probably still feel really tired and emotional. It’s not long to go now before you move onto the second trimester and should start to feel a lot better and start to have a pregnancy glow!! At ten weeks your baby measures about 3.5cm and weighs around 9 grams. His or her eyelids are fused shut and will not open until about week 27. Your baby has elbows and wrists that bend and is developing genitals.

Week Eleven of Pregnancy-First Trimester

It is an extremely good idea to remain fit and healthy during pregnancy, not only will this help your body to cope with the demands that pregnancy places on you but remaining fit and healthy will help you during labour and speed up your recovery after birth. Take a look at our pregnancy exercise page to give you some ideas on how to exercise safely at this special time in your life.

Week Twelve of Pregnancy-First Trimester

You may have your antenatal booking visit this week and your dating/nuchal ultrasound scan. You’ll also have your blood taken for routine blood screening. Your blood is tested for blood group and Rhesus factor, blood sugar, haemoglobin level, syphilis, hepatitis B, rubella and HIV. Your baby is growing well and is about the length of your thumb, he or she now looks like a baby although their head is a little large compared to the rest of their body and has fully formed fingers and toes and all the internal organs are developed. Your baby is also kicking and stretching.

Week Thirteen of Pregnancy-First Trimester

You have now reached the end of the first trimester and the chances of miscarriage are now much lower and all the symptoms associated with the first trimester of pregnancy should be decreasing which hopefully has left you feeling much better and more relaxed. Your baby is now about 7.5cm long and looks just like a baby, your baby can kick his/her legs, turn his/her head and swallow. Swirls of fingerprints are developing on his/her skin.

Healthy Mum - First trimester week by week information