What Blood Tests Are Done During the First Trimester of Pregnancy

Introduction

Seeing a positive pregnancy test can be an emotional and exciting moment, but it also brings up an important question: what should you do next? 

After a home test confirms pregnancy, your doctor will guide you through the next steps, including confirming the pregnancy with a scan and starting your prenatal care. One of the first things you may be advised is to get a few blood tests during pregnancy first trimester, such as an advanced antenatal profile test. While this might feel like a lot, these tests are a normal and important part of early pregnancy care¹. 

Pregnancy is divided into three stages called trimesters, each lasting about 3 months. The first trimester begins at conception and continues up to around 13 weeks and 6 days². This is a very important phase because your baby’s early development begins during this time, and your body also starts adjusting to support the pregnancy. 

Blood tests are an important part of prenatal, or antepartum, care, which means the healthcare you receive during pregnancy. These tests help confirm pregnancy and check for conditions like anaemia, infections, and other health concerns that could affect you or your baby if not detected early. Based on your health needs, your doctor may also suggest additional tests for conditions like thyroid issues or diabetes. These blood tests help identify any problems early so they can be managed in time, supporting a healthy pregnancy¹. 

In this blog, we will explain the first trimester tests, when they are done, what the results mean, and whether they are safe. 

Why Blood Tests Are Important in the First Trimester?

Blood tests in the first trimester are important because they help doctors understand the health of both the mother and the baby early in pregnancy. Doctors advise starting pregnancy care early, usually between 6 to 10 weeks, because this helps identify high risk pregnancies and detect existing health conditions. Early testing also allows doctors to screen for problems at the beginning, so that they can take the right steps at the right time³. 

Below are the main reasons why these blood tests are done: 

1. To confirm pregnancy and understand early progress

Blood tests measure a hormone called beta human chorionic gonadotropin (beta hCG), which helps confirm a pregnancy, when an individual has signs like missed periods or irregular cycles. However, high levels of this hormone do not always mean the pregnancy is normal, because similar levels can also be seen in conditions like ectopic pregnancy (pregnancy outside the uterus), miscarriage, or other abnormal conditions. Doctors may repeat this test after 48 hours, and if beta hCG levels increase as expected, it usually suggests that the pregnancy is progressing normally in the early stage. However, a scan is needed to confirm that the pregnancy is located inside the uterus, which can usually be seen around 5 to 6 weeks¹. 

2. To detect existing health conditions early

Blood tests help identify conditions like diabetes, high blood pressure, and obesity, which can affect how the pregnancy develops if not managed well³. 

3. To check for anaemia and its cause

A haemoglobin test is done to check for anaemia, which usually indicates low red blood cell count. This can happen due to iron deficiency, long-term illness, or lack of vitamins like B12 or folate^4,5. If anaemia is not treated, it can increase the risk of early delivery, poor growth of the baby inside the womb (IUGR), and other complications around birth³. Doctors may do more tests, like checking iron stores (ferritin), vitamin B12, folate, or special blood tests, to find the exact cause of anaemia⁴. Early treatment, such as iron supplementation, can help reduce these risks³. 

4. To determine blood group (ABO type)

Blood group testing is done to check if there is a blood group incompatibility between the mother and baby, which may lead to problems like jaundice in the newborn after birth⁴. 

5. To check Rh factor and prevent immune complications

This is another important test that checks for Rh factor incompatibility between the mother and baby. If the mother is Rh-negative and the baby is Rh-positive, it can cause the mother’s body to react against the baby’s blood cells^3,5. This risk can be greatly reduced with a medicine called anti-D immunoglobulin, if given at the right time³. 

6. To detect infections that can affect the baby

Blood tests are also used to check for infections like HIV, syphilis, and hepatitis B. These infections can pass from the mother to the baby during pregnancy or at birth, but early detection allows timely treatment and prevention⁵. 

7. To support screening for conditions later in pregnancy

Blood glucose testing is used to check for gestational diabetes (diabetes during pregnancy), which is usually done later in pregnancy (between 24 and 28 weeks) but is part of overall monitoring⁵. These first trimester blood tests help confirm pregnancy, detect health problems early, and guide proper care to keep both the mother and the baby safe. 

Types of Blood Tests in Early Pregnancy

During the first trimester, doctors advise several blood tests to check the health of the mother and support the baby’s early development. The key first trimester tests are listed below: 

1. Beta hCG Blood Test (Pregnancy Confirmation)

This is usually one of the first blood tests done. It measures the hormone hCG, which confirms pregnancy. Doctors may repeat this test after 48 hours because a normal pregnancy typically shows a rise in hCG levels (often by about ≥53-66% or higher)⁶. Abnormal beta hCG levels may suggest problems such as ectopic pregnancy or miscarriage¹. 

2. Complete Blood Count (CBC)

This test checks the different types of cells in blood. A red blood cell count helps detect anaemia, white blood cell count shows whether the body may be fighting an infection, while a platelet count helps check for blood clotting disorders. This gives an overall idea of the mother’s health early in pregnancy⁷. 

3. Haemoglobin (Hb) Test

This focuses specifically on detecting anaemia. In the early stage of pregnancy, anaemia is defined as haemoglobin <11 g/dL. This can be due to iron, folate or vitamin B12 deficiency⁴. Identifying low haemoglobin early helps doctors start iron, folic acid, and vitamin B12 supplements to prevent complications in both mother and baby⁵. 

4. Blood Group and Rh Factor Test

This test determines the mother’s blood type and Rh status. If the mother is Rh-negative and the baby is Rh-positive, the mother may produce antibodies that can harm the baby’s red blood cells. Early detection allows doctors to give preventive treatment during pregnancy^5,7. 

5. Indirect Coombs Test

This test is particularly important for Rh-negative mothers. It detects antibodies against baby’s red blood cells in the mother’s blood. A positive test result indicates that the mother’s blood has antibodies against the baby’s blood, which can lead to destruction of the baby’s red blood cells. This might need closer monitoring and appropriate management to avoid complications in the baby⁸. 

6. Infection Screening Tests

Blood tests are done to detect infections such as HIV, hepatitis B, and syphilis. Early diagnosis allows timely treatment, which reduces the risk of passing infections from mother to baby. Additional screening for infections like rubella (checks if the mother is protected against rubella. If she is not immune, the vaccine is given after delivery rather than during pregnancy, as it is a live vaccine), hepatitis C, tuberculosis, and sexually transmitted infections may also be done based on risk^5,7,9.  

7. Blood Glucose Test

This test checks for diabetes. While routine screening for gestational diabetes is usually done later (24-28 weeks), early testing (with oral glucose tolerance test-OGTT) is recommended for women with risk factors such as obesity, history of gestational diabetes, or immediate family member with diabetes. Early detection helps manage blood sugar and reduce pregnancy complications^1,5. 

8. Thyroid Function Tests

Thyroid tests like thyroid-stimulating hormone are usually done at the first pregnancy visit to check if the thyroid gland is working properly. Additional tests are done if there are symptoms of thyroid issues or a history of thyroid disease. Thyroid problems can increase the risk of miscarriage, preeclampsia, and preterm delivery, so targeted testing helps prevent complications³. 

9. Genetic Screening Blood Tests

This includes a first trimester screening test that assesses the baby’s risk of genetic conditions such as Down syndrome, Patau syndrome or Edwards syndrome. Markers such as beta hCG and pregnancy-associated plasma protein A (PAPP-A) are tested between 10 and 13 weeks and 6 days. The results of this test are interpreted along with results of the nuchal translucency (NT) scan done around the same time. This helps parents and doctors make informed decisions and plan further care if needed³.  

Note: These are screening tests and cannot confirm a diagnosis on their own. 

10. Risk-Based Testing

Some tests are done only if risk factors are present, such as a history of gestational diabetes, suspected liver or kidney issues, infections, or genetic conditions. Identifying these risks early allows doctors to plan further tests, monitoring, and treatment¹. Some examples include: 

• Urine test: Helps detect protein or sugar in urine². 
• Liver function tests and creatinine test: May be done to check liver and kidney functioning^10,11. 
• Vitamin D/B12 (if needed): May be checked if deficiency of these vitamins is suspected, especially in vegetarian individuals)¹. 

Together, these tests help doctors understand the mother’s health, detect possible risks, and plan safe care for both the mother and the developing baby. 

When Are These Blood Tests Done?

Blood tests during pregnancy are planned across different stages based on gestational age (weeks of pregnancy) as well as individual risk factors and clinical conditions, with most blood tests during pregnancy first trimester done early (0-13 weeks and 6 days). 

1. Very Early Stage: Pregnancy Confirmation (Before or at First Visit)

The first step is to confirm pregnancy. If it has not already been confirmed by an ultrasound, a beta hCG blood test may be done. However, this test alone cannot confirm a normal pregnancy, so ultrasound (usually around 5-6 weeks) is also done for confirmation¹. 

2. First Trimester (0-13 Weeks and 6 Days): Initial or “Booking” Tests

Most routine blood tests are done at the first antenatal visit, ideally in the first trimester. These include: 

• Complete Blood Count (CBC): This test measures different blood components, including red blood cells, haemoglobin, white blood cells, and platelets⁷. 
• Blood Group and Rh Factor: This test determines your blood type and Rh status and is performed at the booking visit (ideally before 10 weeks of gestation)^5,7. 
• Infection Screening (during booking visit, before 10 weeks of gestation): Includes tests for HIV, syphilis, and hepatitis B, and may also include hepatitis C, rubella, tuberculosis, and sexually transmitted infections^5,7. 

3. Risk Assessment and Special Tests in the First Trimester

During the first visit, the doctor also evaluates risk factors for birth defects, such as maternal age (35 years or older), family history, certain ethnic backgrounds, or pre-existing conditions like diabetes. If risk factors are present, referral for genetic counselling and further screening may be recommended^3,7. 

Some tests are performed only in specific situations: 

• Early diabetes screening at the first visit for high-risk individuals (e.g., individuals with obesity, history of gestational diabetes, and family history of diabetes). 
• Thyroid function tests if there are symptoms or a history of thyroid disease. 
• Targeted infection screening (e.g., for tuberculosis or other infections) if needed¹. 

Additionally, genetic screening tests may be offered: 

• First-trimester screening (10-13 weeks and 6 days) checks for markers such as beta hCG and PAPP-A along with other parameters to assess the risk of chromosomal conditions like Down syndrome. 
• More advanced options, such as cell-free DNA testing, may be done from 10 weeks onwards³. 

Although most baseline tests are done early, some important tests are scheduled later: 

• Blood glucose testing for gestational diabetes is usually done between 24 and 28 weeks⁵. 
• Second-trimester screening tests (15-22 weeks), such as the quadruple test, may be done for further evaluation of the baby’s health. Some screening approaches combine first- and second-trimester results for greater accuracy³. 

Any abnormal results detected during these tests are followed up promptly with additional testing, monitoring, or treatment to ensure the best possible outcomes for both mother and baby¹. 

Are These Tests Safe?

Yes, blood tests are generally very safe. There is no risk to the pregnancy or baby involved in having a blood test. You might feel a small amount of pain when the needle is inserted, and there can sometimes be mild bruising where the needle was inserted. In most cases, these effects are temporary and disappear quickly on their own¹². 

When to See a Doctor?

You should contact your doctor if you notice any symptoms that may need medical attention during pregnancy, such as: 

• Bleeding or stomach cramps 
• Fever, chills, or other signs of infection 
• Pain or burning while passing urine 
• Unusual vaginal discharge or discharge with a bad smell 
• Ongoing vomiting or very severe nausea 
• Any doubts or worries about your health or pregnancy 

If anything feels unusual or uncomfortable, it is always better to check with your healthcare provider². 

Also Read: PCOD Diet Chart: Foods to Eat, Avoid, Meal Plan & Lifestyle Tips

Conclusion

First trimester blood tests are important in early pregnancy care. They help doctors check the mother’s health and the baby’s early development. These tests can identify conditions such as anaemia, infections, diabetes risk, and blood group or Rh factor incompatibilities at an early stage, allowing for timely care and monitoring during pregnancy. This reduces the chance of complications and supports better pregnancy outcomes. First trimester blood tests are a simple and safe step that provides important information and helps provide a healthy and well-managed pregnancy journey for both mother and baby. 

Frequently Asked Questions (FAQs)

References

1. Karrar SA, Vadakekut ES, Hong PL. Initial Antepartum Care. In: StatPearls. StatPearls Publishing; 2026. Accessed April 30, 2026. http://www.ncbi.nlm.nih.gov/books/NBK570635/ 

2. Prenatal care in your first trimester: MedlinePlus Medical Encyclopedia. Accessed April 30, 2026. https://medlineplus.gov/ency/patientinstructions/000544.htm 

3. Prenatal Care: An Evidence-Based Approach | AAFP. Accessed April 30, 2026. https://www.aafp.org/pubs/afp/issues/2023/0800/prenatal-care.html#abstract 

4. Karrar SA, Vadakekut ES, Hong PL. Table. Recommended Initial Prenatal Serum Laboratory Studies. August 12, 2024. Accessed April 30, 2026. https://www.ncbi.nlm.nih.gov/books/NBK570635/table/article-105819.table0/ 

5. Maternal, Newborn, Child and Adolescent Health and Ageing Department. Accessed April 30, 2026. https://www.who.int/teams/maternal-newborn-child-adolescent-health-and-ageing/handbooks/programme-manager-s-handbook-mncah/recommendations-on-interventions-along-life-course/maternal 

6. Larraín D, Caradeux J. β ‐Human Chorionic Gonadotropin Dynamics in Early Gestational Events: A Practical and Updated Reappraisal. Hemida R, ed. Obstet Gynecol Int. 2024;2024(1):8351132. doi:10.1155/2024/8351132. https://www.researchgate.net/publication/378812239_b-Human_Chorionic_Gonadotropin_Dynamics_in_Early_Gestational_Events_A_Practical_and_Updated_Reappraisal 

7. Routine Tests During Pregnancy | ACOG. Accessed April 30, 2026. https://www.acog.org/womens-health/faqs/routine-tests-during-pregnancy 

8. Izetbegovic S. Occurrence of ABO And RhD Incompatibility with Rh Negative Mothers. Mater Socio Medica. 2013;25(4):255. doi:10.5455/msm.2013.25.255-258. https://pubmed.ncbi.nlm.nih.gov/24511269/ 

9. Serological testing for immunity to rubella is recommended before or after receiving rubella-containing vaccine in certain circumstances. 2023. Doi: https://immunisationhandbook.health.gov.au/recommendations/serological-testing-for-immunity-to-rubella-is-recommended-before-or-after-receiving-rubella-containing-vaccine-in-certain-circumstances 

10. Dajti E, Bruni A, Barbara G, Azzaroli F. Diagnostic Approach to Elevated Liver Function Tests during Pregnancy: A Pragmatic Narrative Review. J Pers Med. 2023;13(9):1388. doi:10.3390/jpm13091388. https://pubmed.ncbi.nlm.nih.gov/37763154/ 

11. Wiles K, Bramham K, Seed PT, Nelson-Piercy C, Lightstone L, Chappell LC. Serum Creatinine in Pregnancy: A Systematic Review. Kidney Int Rep. 2019;4(3):408-419. doi:10.1016/j.ekir.2018.10.015. https://pubmed.ncbi.nlm.nih.gov/30899868/ 

12. Pregnancy Test: MedlinePlus Medical Test. Accessed April 30, 2026.  https://medlineplus.gov/lab-tests/pregnancy-test/ 

13. Tailored Prenatal Care Delivery for Pregnant Individuals | ACOG. Accessed April 30, 2026. https://www.acog.org/clinical/clinical-guidance/clinical-consensus/articles/2025/04/tailored-prenatal-care-delivery-for-pregnant-individuals 

14. Poon LC, McIntyre HD, Hyett JA, Da Fonseca EB, Hod M. The first-trimester of pregnancy – A window of opportunity for prediction and prevention of pregnancy complications and future life. Diabetes Res Clin Pract. 2018;145:20-30. doi:10.1016/j.diabres.2018.05.002. https://pubmed.ncbi.nlm.nih.gov/29852233/ 

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