What to Expect During Your First Trimester
Updated: Sep 17, 2021
There's a lot going on in there as your baby begins to develop. Here's more about what to expect, including your first trimester to-do checklist.
You may not look pregnant yet — but chances are you're feeling it. That's because a flood of pregnancy hormones is prepping your body to play baby hostess for the next nine months — so you could be in line for quite a few aches and pains, from fatigue to flatulence. While you might be less than thrilled with some of these symptoms, try to remind yourself that these temporary discomforts are part of the incredible process that's happening inside: You're growing a child!
How Long Is the Firs Trimester?
The first trimester lasts from week 1 through the end of week 13 of pregnancy.
Not sure what week you are in your pregnancy? The first step to nailing your current week down is to calculate your due date. Keep in mind that your date might change (especially if you have irregular periods), so try to go with the flow.
Baby’s Growth During the First Trimester
During the first trimester alone your baby changes from a single fertilized cell (a zygote), to the embryo that implants itself in your uterine wall, to a peach-sized bundle of growing limbs and body systems. Organs take shape, and baby starts to move. Here are a few of the big highlights happening in this exciting time:
Baby’s bones: By about week 6, baby starts to sprout arms, legs, hands and feet — and fingers and toes around week 10.
Hair and nails: Skin begins forming between weeks 5 and 8, with hair follicles and nail beds forming around week 11.
Digestive system: By about week 8, baby’s intestines will begin forming, and your baby will have already gone through two sets of kidneys (with the third and final set on its way!).
Sense of touch: Your baby will have touch receptors on his face (mostly lips and nose) around week 8. By week 12, he’ll have receptors on his genitals, palms and the soles of his feet.
Eyesight: Optic nerves (which pass info from the eyes to the brain and back) and lenses begin to form by week 4, with the retina beginning to form around week 8.
Heart: By week 5, the tube that will become your baby’s heart begins to beat spontaneously. It will become stronger and more regular — and you’ll be able to hear it! — around week 9 or 10 (though sometimes later, depending on your baby’s position in your uterus).
Brain: By about week 8 of pregnancy, your baby’s brain will be wiggling his developing limbs.
Sense of taste: Your baby will have developed taste buds that connect to his brain by about week 8 — but he’ll need taste pores before he can taste the surrounding amniotic fluid (which, by the way, tastes like your most recent meal).
Other major first-trimester milestones include the formation of muscles, the production of white blood cells to fight off germs and the development of vocal cords.
Changes in Your Body
A lot happens for you in the first trimester, too. A couple of the most common early symptoms of pregnancy you may experience:
Morning sickness: Unfortunately it doesn't just strike in the morning — and it typically starts up by about week 6 of pregnancy. Ginger tea or drops might help, as can small but frequent meals. If it’s severe, you might want to consider talking to your doctor about medications to treat the symptoms of pregnancy-related nausea.
Tender breasts: So tender, so tingly, and so big! You might be wondering where your old boobs went by about week 6.
Mood swings: You may (or may not) feel up, then down, then up again by week 7. If you have a history of depression or think it might be more serious, talk to your doctor about getting screened for prenatal depression.
As your pregnancy progresses this trimester, you may experience plenty of other pregnancy symptoms — heartburn, constipation, metallic taste, food aversions and headaches. Hang in there: The second trimester will offer welcome relief! Keep in mind, too, that every woman is different. So just because your mom or sister reported cramping or frequent urination doesn't guarantee either symptom will happen to you too.
Your baby is still very small — which means all told you only need to gain about three to four pounds in your first trimester. If you’re suffering from appetite loss, you might even lose a couple of pounds. That’s OK, too — as long as your pregnancy weight gain picks up steam in the second and third trimesters. For now, just focus on eating frequent light meals of any high-density nutritious foods (e.g., avocados, yogurt, bananas, whole grain bread or crackers) when you can stomach it.
Feeling extra ravenous? Try to keep a check on your caloric intake during pregnancy in check: You don’t actually need any extra calories during your first trimester (though your intake will go up in the second and third trimesters). If you do end up gaining more than is recommended now, all is not lost. Just focus on getting back on track over the duration of your pregnancy.
Symptoms to Have Checked Out
With all of the changes going on in your body during pregnancy, you may wonder what’s normal — and what’s not. In many cases, that odd twinge is not a cause for concern. However it’s also important to understand that your risk for miscarriage is the highest during the first trimester. Here are a few symptoms that do always warrant a call to your doctor:
Heavy vaginal bleeding
Severe abdominal pain
Fever over 101.5 F, chills and/or backache
Severe puffiness in the hands/face
If you experience any of the above symptoms, call your doctor’s office right away. If you don’t get someone on the phone within a few minutes, head to the nearest ER.
First trimester to-dos
Start a prenatal vitamin. If you haven’t already, start taking a prenatal vitamin immediately — doing so in the first trimester has been shown to greatly reduce the risk of neural tube defects (like spina bifida).
Choose your practitioner. There are a number of different practitioners you can choose for your pregnancy, from OB-GYN to midwife to family physician. So take time to consider your options and pick the right practitioner for your needs.
Book your first ob-gyn visit. Your doctor will review your medical history and perform a thorough physical exam. You'll likely undergo a battery of tests, including a Pap smear, urinalysis and blood work to determine your blood type and Rh status, hCG levels and the presence of any infections. You'll likely have an initial ultrasound to confirm a heartbeat, date your pregnancy and be sure things are progressing as they should. You might also be screened for genetic illnesses or diabetes, depending on your family history. While your practitioner will ask lots of questions, be prepared to ask plenty of your own: Now's the time to inquire about the safety of any medications you’re currently taking, help for quitting smoking or anything else that’s on your mind.
Consider getting a SneakPeek. If you're curious about your baby's gender, a SneakPeek Clinical DNA test will let you discover your baby's gender at 7 weeks into pregnancy, months earlier than ultrasounds! Trusted by over 450,000 moms and obstetricians, clinically-proven to be 99.9% accurate.
Consider genetic tests. You’ll likely have a nuchal translucency screening (between weeks 10 and 13 of pregnancy) to look for Down syndrome and congenital heart defects; based on your risks, your practitioner may also recommend NIPT around week 9 (a noninvasive blood screening that looks for chromosomal abnormalities) and/or invasive but more definitive prenatal tests (chorionic villus sampling or amniocentesis).
Look into health insurance options. The cost of pregnancy varies based on a number of factors (and it’s a whole lot more expensive if you don’t have health insurance). So now’s the time to sign up for a plan or review the terms of your policy, focusing on your premiums and co-insurance to keep your overall costs as low as possible. The good news: You can still take steps to reduce your prenatal insurance costs.
Make a budget. Growing your family is an excellent — and necessary — time to reevaluate your monthly expenses. So learn the cost of having a baby, then set up your monthly budget.
Eat right. Now’s the time to cut down on caffeine, as well as to learn which foods to avoid and which to feature in your pregnancy diet so you can stock your kitchen accordingly.
Carve out time for fitness. There are lots of benefits of exercise during pregnancy for you and baby — which can be good motivation to get your 30 minutes of physical activity most days of the week. Not sure where to start? Try these pregnancy-friendly workouts.
Have sex, if you feel like it. It’s fun and safe for baby — plus it has benefits for both of you.
Start thinking about baby names. If you don’t have a baby name in mind, it’s never too early to start tossing around ideas. Check out these 10 tips for naming your baby for guidance.
Plan to announce your pregnancy. Think about how and when you want to tell your friends and family the good news, and if and when you’ll announce on social media. Most women wait until the end of the first trimester to do so, when the risk of miscarriage is lower. And if you’re employed, start thinking about when to tell your boss your pregnant and what to say; do your research in advance to understand your company’s maternity leave policies.
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