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What Happens to Your Body During Each Stage: First Trimester

30 April 2026
Pregnancy Weight Gain Calculator

Pregnancy is a period characterized by constant physical and emotional shifts. Throughout your pregnancy, you should attend regular prenatal check-ups with your OB-GYN, receiving referrals for tests and guidance for healthy lifestyle.

Expected physical changes

Your body begins producing hCG, the hormone responsible for the suspension of your menstrual cycle. These hormonal shifts may affect your level of fatigue, mood and breast sensitivity, which become fuller and more tender.

Common symptoms

Nausea and heartburn are common symptoms during this stage. You can seek natural solutions, such as ginger, almonds, and small meals. However, in severe cases, it is important to consult your physician regarding supplements or medications that are safe for use during pregnancy.

Medical prenatal follow-up

The first visit to your OB-GYN is comprehensive, and includes risks assessment, determining the exact gestational age, and an open discussion about lifestyle and emotional support. During this visit, you will receive referrals for tests and vaccinations.

Vaccinations during pregnancy

It is recommended to get vaccinated against the flu (during the winter) to protect both you and the fetus, and to check your previous vaccinations.

Medical check-ups

The first trimester is characterized by various tests: an initial ultrasound, blood and urine tests, nuchal translucency screening, and genetic carrier screening for hereditary diseases.

Recommended vitamins and supplements
Folic acid, iodine, and vitamin D are essential for fetal development. These may be taken as individual supplements or as part of a combined multivitamin supplement.

Weight and nutrition during pregnancy

The recommended range for weight gain is determined by your medical team based on your BMI. It is important to tailor your diet to meet both your needs and those of your fetus. It is recommended to avoid foods that pose a  risk of infection (such as raw fish, raw meat, and unpasteurized dairy products), limit caffeine consumption, and completely abstain from alcohol.

When to seek immediate medical attention

In cases of heavy bleeding, severe abdominal pain, persistent vomiting or fainting, you must seek immediate medical attention.

Emotional shifts

Pregnancy triggers a mix of emotions and anxieties. It is essential to receive support from those around you. If emotional challenges persist for more than two weeks and interfere with your daily functioning it is important to seek professional support.  

Pregnancy is a period characterized by constant physical and emotional shifts. It is typically divided into three trimesters – each bringing its own unique changes. In this article we will outline the medical procedures, essential tests and ways in which to maintain a healthy lifestyle for both you and your fetus during the first trimester (weeks 1 to 12).

It is important to point out that throughout your pregnancy you should attend regular prenatal check-ups with your OB-GYN. In addition to these visits, a medical team is available to address your questions, including prenatal care nurses, Tipat Halav, nurses and midwives. We recommend checking with your HMO regarding the services available to you.

Prenatal medical follow-ups

If you did not visit your physician before becoming pregnant, do not be concerned. The first visit, between week 6 to 12, covers the majority of tests and questions related to the beginning of pregnancy. If you already had a preconception visit, the first prenatal appointment will be shorter and will complement the previous one. Here is what to expect during this visit:

Gestational age (the week of pregnancy) is typically determined based on the first day of your last menstrual period (LMP). In cases of uncertainty, or irregular cycles, an ultrasound may be performed. Based on the gestational age, your estimated due date (EDD) is calculated to tailor your upcoming prenatal tests.

Your physician will inquire about your medical  and obstetric history (including underlying conditions, past surgeries, or current medications). If close monitoring is required, you will be referred to a clinic or a high-risk pregnancy specialist.

This includes monitoring your blood pressure, pulse, and weight, as well as checking for edema in the face and hands. You will also be referred for further tests, such as a urine protein screen.

If you have not yet undergone these tests, the medical team will explain the available options, so you can choose the screenings most suitable for you and your family. If necessary, you will be referred for genetic counseling.

The medical team will ask you about your relationship status, including your sense of safety at home and whether you have any concerns about violence, as well as any past difficult events (such as trauma, violence, or sexual abuse). You may be asked about difficulty regarding gynecological exams, or a history of sexual trauma. It is essential to share these situations with the medical staff. It is important for you to know that you may share, and that the exam can be tailored to your pace and comfort. If you are a single mother, a surrogate, or part of an LGBTQ+ family, share this with your physician. This helps provide tailored support for both you and your family, including guidance on exercising your rights and information on topics such as breastfeeding for everyone involved in raising the baby, regardless of gender.

You will receive guidance on proper nutrition, including vitamins and dietary supplements that are vital, such as folic acid, vitamin D, and iodine.

The medical team will review your past vaccinations and recommend completions if needed.

Note

Note

If you did not discuss all of these topics with your physician, you may consult a prenatal care nurse or a Tipat Halav nurse to receive the information you need.

Physical Changes

In the early stage of pregnancy, the uterus and the placenta—the organ responsible for delivering oxygen and nutrients to the fetus—begin to develop. The placenta secretes a hormone called hCG, and as it grows, hormone levels rise. This increase leads to the cessation of menstruation and is usually what leads women to discover the pregnancy, either through a home test or a laboratory blood test that measures hormone levels in the body.

High hormone levels also affect fatigue, nausea, and mood changes. For most women, these symptoms improve after a few weeks, while for others they may persist for a longer period during pregnancy.

The breasts also begin to change: they become fuller and more sensitive, the skin around the nipples darkens, and the body undergoes hormonal adjustments that can sometimes be felt even before the pregnancy is officially diagnosed.

Common Symptoms

  • Nausea
  • Heartburn
  • Nausea: Nausea is very common at this stage. Some “home remedies” may sometimes help, such as natural almonds, ginger, plain crackers, or dry toast.
    If you are experiencing severe nausea, this is the time to contact your gynecologist, as there are supplements and medications that may help. Note: Most medications for nausea are not safe during pregnancy, so it is very important to consult a healthcare professional before taking any medication.
  • Heartburn: Hormonal changes and pressure from the uterus on the stomach cause many women to experience heartburn at different stages of pregnancy.
    There are several ways that may help you:
    1. Eat small, varied meals frequently and chew food thoroughly.
    2. Separate drinking from eating solid food.
    3. Avoid carbonated drinks and fatty foods.
    4. Safe physical activity and pelvic floor strengthening may help reduce heartburn.

Note

Note

If these solutions do not provide relief and you are suffering significantly, you should contact your physician. In any case, do not take any medications without consulting a medical professional authorized to confirm they are safe for use during pregnancy.

Adapting your diet for pregnancy

From the moment you discover you are pregnant, you will have to adapt your diet and particularly, to provide your body with sufficient calories and protein. From now until childbirth, you will have to refrain from several types of foods, including unpasteurized dairy products and aged cheeses, raw fish, raw meat, foods high in saturated fat, trans fat, cholesterol, and alcohol in any quantity.

Additionally, it is advisable to minimize consumption of snacks, sweets and artificial sweeteners, salt, coffee and caffeine.

More on recommended pregnancy diet

Recommended range for weight gain

During your first prenatal follow-up visit, your height and weight will be measured to calculate your BMI (Body Mass Index) and tailor a recommended range for weight gain during your pregnancy. In your subsequent visits, you will be weighed to monitor your progress, and ensure it is a healthy gain.

It is important to know that weight gain is a natural and necessary process. Healthy weight gain can help both you and your baby prevent complications, including gestational diabetes, preeclampsia, pre-term delivery, or the need for a C-section. If the weight gain exceeds the expected range, you may be referred to a dietitian.

During the first trimester, if your BMI is within the normal range, the recommendation for a single-fetus pregnancy is to gain between 0.5 to 2 kilograms during the first trimester. Recommended weight gain chart (single fetus) based on BMI at the start of pregnancy:

Total recommended weight gain BMI status

BMI category at the start of pregnancy
BMI < 18.5  Underweight 12.5-18kg
​18.5 ≤ BMI < 24.9  Normal weight 

11-16kg
​​25 ≤ BMI < 29.9  ​ Overweight

7-11.5kg
​​30 ≤ BMI  ​ Obese 5-9kg

Recommended vitamins and dietary supplements during pregnancy 

Several vitamins and dietary supplements are recommended during pregnancy:

  • Folic acid: Recommended throughout the childbearing years. If you did not take it prior to pregnancy, now is the time to start.
  • Iodine: Recommended during the entire pregnancy and while breastfeeding.
  • Calcium: Recommended during the entire pregnancy and while breastfeeding.
  • Vitamin D: Recommended during the entire pregnancy and while breastfeeding.
  • Omega-3: As a supplement or by consuming fatty fish, such as salmon and trout, rich in Omega-3.
  • It is recommended to include iron in your list of supplements from the end of the third month.

It is advisable to read more about each supplement in detail.

Important to note: If this list seems overwhelming, most of these supplements can be taken together in a single, combined pill known as prenatal multivitamin, containing the recommended doses of the required dietary supplements: iron, folic acid, calcium, and iodine.

Vaccinations during pregnancy

Even before coming with your baby to Tipat Halav, it is recommended that you get vaccinated yourself during your pregnancy. During the winter, it is recommended to get vaccinated against the flu, and it is best to get vaccinated now. It is possible to do it during any week of pregnancy. The vaccine will reduce the chances of you getting the flu, which is a disease that can lead to complications in pregnant women, and will also protect your baby. If you are in a risk group – a COVID-19 vaccine is recommended. Later in your pregnancy, you will be asked to get additional vaccines.

Medical check-ups

The following tests, recommended by the Ministry of Health, can be performed within the specific weeks listed below:

  • Genetic screening tests: If you have not done so prior to pregnancy, it is recommended to undergo genetic screening tests for severe hereditary diseases.

  • Weeks 6-12 of pregnancy: An ultrasound to determine gestational age, pregnancy viability, and the number of fetuses.
  • Weeks 11-13 of pregnancy: Nuchal Translucency (NT) by ultrasound scan to assess the risks of Down Syndrome and fetal anomalies.
  • Weeks 11-13 of pregnancy: CVS (Chorionic Villus Sampling): To examine fetal chromosomes and diagnose genetic disorders.
  • Weeks 11-22 of pregnancy: Amniocentesis: To examine the fetal chromosomal profile and diagnose genetic disorders.
  • Weeks 11-13 of pregnancy: First-trimester screening: Including blood tests for PAPP-A and free beta-hCG, combined with a nuchal translucency (NT) scan.
    NIPT (Non-Invasive Prenatal Testing) can also be performed during these weeks.
  • First trimester blood tests: A complete blood count (CBC), fasting glucose, thalassemia, blood type and Rh antibody screen, syphilis, urine, HIV, Hepatitis B, and antibody screen for Rh-negative women.
  • Checking rubella vaccination status and guidance on postpartum vaccination.

When to seek immediate medical attention

The following conditions require immediate medical evaluation at a medical center (during the morning), or at an Emergency Room (at night):

  • Bleeding heavier than a normal period.
  • Severe abdominal pain.
  • Persistent vomiting.
  • Loss of consciousness or fainting.

Please note: You can also consult your HMO's Nurse Advice Line if you are unsure where to go.

Emotional changes

The beginning of pregnancy is often characterized by a mix of emotions, including excitement, curiosity, occasional fear, confusion or doubts about the future and one's parental capabilities.​

Hormonal shifts can cause sharp mood swings, and some women report a sense of detachment or a gap between the image of the 'magical pregnancy'  ideal and their actual experience.

Emotional support from your spouse, friends, or family, combined with some rest, regular meals, and moderate physical activity, can help regulate both physical symptoms and the emotional toll.

Information overload can also increase anxiety; therefore, it is recommended to choose a few trusted professional sources and consult your prenatal care team  (physician or nurse) with any questions you may have.

For further information on emotional changes during pregnancy

Please note: If these feelings persist for more than two weeks, cause you considerable distress, or make it difficult to function, do not face this alone; Contact your OB-GYN or your primary care physician, a nurse, a psychologist or a social worker to receive the support and tools that will help you feel better.

Seeking help early can prevent further difficulties, strengthen your resilience, and protect both you and your baby.

For further reading

Note

Note

If these feelings continue for more than two weeks, cause significant distress, or make it difficult for you to function, don’t go through it alone. It is highly recommended to reach out to your gynecologist or family doctor, a nurse, a psychologist, or a social worker to receive support and tools that can help you feel better.

Seeking help early can prevent difficulties, strengthen your resilience, and support both you and your baby.