The first trimester of your pregnancy is a time of great change for your baby and for your body, says Tiffany Brown.
From the first few weeks when the embryo is implanted in your uterus, right through to the 14-week mark when an ultrasound scan may clearly show you baby-like characteristics such as arms, legs, and even ngers and toes, this rst trimester of your pregnancy is ultimately crucial for your baby’s development.
It is also an important time for a pregnant woman and her partner to wrap their heads around what lies ahead. And it’s a time where you need to look after yourself, and be supported by those who love you, as you embark on both a physically and psychologically life- changing journey towards parenthood.
How your baby grows
Weeks 1 to 3
The medical de nition of the pregnancy term of a 40-week gestation has conception occurring around two weeks after your last period starts. As such, weeks one to two are actually a “non-pregnant” time.
During week three, however, fertilisation and implantation get that pregnancy ball rolling. Dad’s sperm gets together with Mum’s egg and forms a one-celled entity called a zygote, which typically has 23 chromosomes from each parent. These 46 chromosomes determine the sex, eye and hair colour, and to an extent the personality and intelligence of your little one.
Weeks 4 to 6
By around week four, the zygote has travelled down the fallopian tube to your uterus, and begins the process of implantation. This rapidly-dividing, two-sectioned cluster of cells, called a blastocyst, is forming an embryo inside, and a protective layer of cells on the outside. Once in contact with the uterine wall, the blastocyst burrows inside for nourishment. (Hurrah! Impantation!) Also beginning to form now is the placenta, which will produce hormones, provide nutrition, and deal with baby’s waste products in the coming weeks.
As early as five weeks into the pregnancy, your baby’s brain, spinal cord, heart, and other organs begin to form. The embryo now consists of three layers. The ectoderm – or top layer – will form the skin, central and peripheral nervous systems, eyes, inner ears, and connective tissues. The central layer – or mesoderm – is the foundation of
the heart, the early circulatory system, bones, muscles, kidneys, and much of the reproductive system. The endoderm, or inner layer of cells, becomes a mucous membrane-lined tube where your baby’s lungs, intestines, and bladder develop. Despite beginning the important business of forming all these essential body parts, your baby still looks rather like a tadpole at this point, and measures just about a quarter of a centimetre in length.
Development continues to ramp up around week six. The neural tube running along your baby’s back closes, and if you have a scan at around this time, you should see a pulse where the chambers of the tiny heart are beginning to pump blood. Basic facial features start to take shape, with dark spots where the eyes will be, openings for the nostrils and pits to mark the ears. Baby’s body starts to curl into a “C”, and small buds appear, destined to become arms and legs.
Five weeks into pregnancy, your baby’s brain, spinal cord, heart and other organs begin to form. But it still looks more like a tadpole than a baby at this stage, and measures about a quarter of a centimetre long.
Weeks 7 to 9
By the end of week seven, your baby is not quite as big as a cashew nut. Even still, their face is continuing to take shape, with nostrils becoming visible and eye lenses beginning to form. The brain continues to develop, as nerve cells reach out to each other, forming primitive neural pathway connections. The arm buds that appeared last week now look like tiny paddles.
From around the eight-week mark through to about halfway, or 20 weeks, there will be rapid growth, including major development of the heart, brain, and the other body parts that were formed in the rst few weeks. At eight weeks, your baby’s body starts to straighten out as arms and legs grow longer. Fingers, upper lip, and nose are forming, along with the shell- shaped parts of the ears. Most excitingly, the eyes are now visible as eyelids and ears continue to develop.
By now the placenta has developed to the point of taking charge of producing hormones, giving many mums welcome relief from symptoms of morning sickness. Through the ninth week, baby’s arms grow in length and form bones, and begin to bend at the elbows. Wrists, ankles, fingers, and toes have also formed. Despite measuring a mere 20mm in length, your baby is looking distinctly more baby-like.
What NOT to do in the first trimester
Whether you know you’re pregnant or not, give the booze a swerve. Your body will thank you for it either eay. Also on the don’t list in the first trimester:
- Don’t smoke or take drugs
- Don’t drink alcohol.
- Don’t take medications or nutritional supplements without checking they are safe for use in pregnancy.
- Don’t get over-heated.
- Don’t stress out.
- Don’t eat certain high-risk foods, like sushi (sigh!), soft-serve ice-cream, raw sh, pre-prepared deli meats, sandwiches, and salads, or any leftovers that have not been re-heated to piping hot (for a complete list of foods you are recommended to avoid during pregnancy, see health.govt.nz/ your-health/pregnancy- and-kids/helpful-advice- during-pregnancy)
Weeks 10 to 12
Week 10 brings the development of the neck, as the head becomes more rounded and the eyelids begin to close to protect the developing eyes. All the vital organs are now formed and functional, and your baby is quite active now, swallowing uid and kicking its arms and legs around.
External genitalia form during week 11, and while the head still measures around half the length of your baby, the body is beginning a big growth spurt to catch up. If your baby is a girl, she has about two million eggs in her tiny ovaries. By the time she is born, this number will have dropped to about a million, and will continue to drop away as she grows up. (Now you can see why you might have had a bit of a job conceiving her!) With all requisite parts now in place, your baby is officially described as a foetus.
With low-set ears, fused eyelids and widely separated eyes, at 12 weeks along in your pregnancy your baby’s face now has a distinctly human pro le. Re exes are developing as foetal nerve cells multiply rapidly and synapses, or neural pathways, form. Baby can close their ngers, curl their toes, and clench their eye muscles.
Weeks 13 to 14
Fingernails have now been formed, and tiny fingerprints appear at the top of your baby’s fingers. Week 13 also sees your baby exercising the sucking muscles in their cheeks, practising their “rooting” instinct. This is the instinct that kicks in to guide your baby to search for your nipple for sustenance and comfort soon after birth.
By week 14, your baby will measure around 8cm from crown to rump and weigh about 40 grams. The kidneys have begun to produce urine, which is released into the amniotic uid. Fine, downy hair called lanugo begins to grow this week, protecting your baby’s ultra-thin skin. Hair on the head and eyebrows begins to grow too. Impulses in the brain are starting to direct facial expressions like squinting, frowning, and grimacing, exercising baby’s facial muscles.
What about mum?
Even though you may not become aware of your pregnancy until a few weeks have passed, it’s important to try to maintain a healthy lifestyle if you are in a position where you may become pregnant. Focus on getting your nutrition, exercise, and stress management in balance. This will stand you in great stead for pregnancy and caring for a young baby.
A healthy, balanced diet is important to ensure you are in tip-top shape to nurture your baby to term. In utero, babies pull everything they need from their mum, and if you’re not suf cient in certain nutrients, your pregnancy can leave you in deficit, making it harder for you to recover from birth, and more dif cult for you to care for your infant. Particularly focus on your iron, calcium, and energy stores, and seek guidance from a health practitioner or nutritionist with expertise in caring for women through pregnancy.
The first physical change you’re bound to experience in the early weeks of your pregnancy is fatigue, or at least an increase in tiredness. Nausea is the next common symptom. Also called “morning sickness”, pregnancy nausea may strike at any time and in varying degrees from as early as three weeks.
The biological explanation for tiredness and nausea gives the cause as the overwhelming task your body is undertaking. But the school of old wives’ tales may also give you some comfort. They speculate the body tires in order to provoke rest, which helps your baby grow through the magni cent early changes with plenty of energy. And perhaps nausea kicks in to veer expectant mothers away from risky choices, particularly in relation to food consumption.
Many women will experience pregnancy headaches, mostly caused by hormones and sometimes by postural changes. Drink plenty of water during the day, be mindful of your posture, avoid straining your eyes, and eat small, nutritious meals several times throughout the day. Neck, shoulder, face, or scalp massages can help, as can a warm or cool compress on your forehead or the back of your neck.
Emotionally, you are experiencing an unprecedented time of change and anticipation. Many women struggle with such an emotional load, and may slide into perinatal depression. If you feel down in the dumps for longer than a week,
reach out to your healthcare professional, LMC (lead maternity carer), or even a sympathetic friend or family member. What you’re feeling is very normal, and there are solutions to getting back on track and enjoying the rest of your pregnancy.
Exercise can help tremendously with fatigue, morning sickness and stress. Many mums manage to continue with their physical activity all the way through pregnancy. For the majority, however, it’s important just to try and maintain a regular, moderate level of activity. Walking, swimming, and yoga are perfect exercises to do through pregnancy, so try to work at least one of these pursuits into your daily schedule, beginning in the first trimester.
Another important component to a successful pregnancy is ensuring you manage to t in some relaxation time. This is particularly relevant if you’re a career girl, have a busy lifestyle, or nd it hard to “switch off”. Life as you know it carries on through the early part of pregnancy, and often you’ll choose not to let anyone know that you’re pregnant, adding another dimension of pressure to your rapidly changing world. Even the most chilled-out women can experience great emotional turmoil as they begin to come to terms with the enormous journey ahead of them.
Pregnancy hormones also begin to kick in during the rst trimester, bringing this immense emotional landscape into even sharper focus. Exercise can help get you into a meditative state (now there’s a nice “two birds, one stone” scenario!). Talk with your partner, family, or friends, create some “me time” to indulge in the activities that centre you, enjoy a relaxing bath at the end of the day, or use self-directed or guided meditation to soothe your busy mind and keep your spirit in balance. Again, getting into the habit of regularly relaxing in the rst trimester will set you up well for the rest of your pregnancy.
As you enter the second trimester, many women find their pregnancy symptoms ease off until the “big and uncomfortable” stage creeps up towards the end. If you are able, the second trimester is the perfect time to take a break. Many women go on holiday around this time, when comfort is at its peak, and nd it a wonderful way to connect with their partner and prepare themselves both mentally and physically for the rest of their pregnancy and beyond.
Share this page
BUMP&baby
BUMP & baby is New Zealand’s only magazine for pregnancy and early babyhood. Our team of mums and mums-to-be understand what it’s like to be pregnant in this connected age, and that’s why BUMP & Baby online is geared toward what pregnant women and new mums really want to know.
Other articles of interest
Giving birth naturally — your way
With all of the birth techniques available, how do you know which one is right for you?
Beyond the baby blues
It’s normal to feel a bit down following childbirth. But what if your feelings don’t improve, or you aren’t coping? You may have postnatal depression, also known as PND
