A Complete Guide to Pregnancy Care: Tests, Ultrasound, and Medical Monitoring by Trimester
Author's clinical commentary: doctor Korzhykov, family doctor (VALINTERMED company)
Pregnancy is a physiological condition accompanied by profound hormonal, anatomical, and metabolic changes in a woman's body. Although most pregnancies proceed without complications, this period requires systematic medical monitoring to detect potential abnormalities early, prevent complications, and ensure optimal conditions for fetal development.
Antenatal care (pregnancy monitoring) includes a combination of clinical, laboratory, and instrumental examinations aimed at assessing the condition of the mother and fetus at different stages of gestation. Modern pregnancy management protocols are based on evidence-based medicine principles and are adapted depending on the gestational age, risk factors, and the individual characteristics of the patient.
This material is an expanded protocol for monitoring low-risk pregnancies, structured by trimester. I have endeavored to explain simply and clearly how pregnancy care is performed in Spain. The scope of examinations may vary depending on the individual's medical history, risk factors, and the progress of the pregnancy.
This article provides an extensive guide to pregnancy care, detailing the examinations, tests, and screenings performed in each trimester, with clinical explanations that are understandable to both healthcare professionals and patients.
General principles of pregnancy management
Monitoring of a pregnant woman is carried out by an obstetrician-gynecologist and includes:
- regularly scheduled visits;
- dynamic assessment of the condition of the mother and fetus;
- laboratory and instrumental examinations within the established timeframes;
- preventive measures;
- individual adjustment of the observation plan in the presence of risk factors.
Pregnancy is conventionally divided into three trimesters, each of which is characterized by its own diagnostic tasks:
- First trimester (0–13 weeks) — confirmation and early assessment of pregnancy, primary screening;
- Second trimester (14–28 weeks) — detailed assessment of fetal anatomy and identification of metabolic disorders;
- Third trimester (29–40 weeks) — preparation for childbirth and monitoring of the fetus’s condition.
First trimester of pregnancy (0-13 weeks): tests, Ultrasound and early screening
VALINTERMED Pregnancy Monitoring Principles
- Evidence-based medicine and clinical appropriateness of the prescriptions.
- Reasonable sufficiency: we assign what influences the tactics of management.
- Clear explanations: the patient understands the purpose of each analysis and decision.
- Personalization: the plan is adjusted if risk factors are present.
The first trimester of pregnancy is a key monitoring stage, as it is during this period that all fetal organs and systems are formed, and the subsequent pregnancy management strategy is formulated. 7–9 weeks A pregnant woman typically meets her obstetrician-gynecologist for the first time, who will be supporting her throughout her pregnancy. At this stage, a trusting doctor-patient relationship is established, a detailed medical and obstetric history is collected, individual risk factors are assessed, and a personalized care plan is developed.
It is during the first trimester that basic laboratory tests and ultrasound diagnostics are performed to confirm an intrauterine pregnancy, assess its viability, determine the gestational age, and identify potential abnormalities early. Early screening, including ultrasound and biochemical markers, plays a crucial role in assessing the risk of fetal chromosomal abnormalities and allows for the timely determination of the need for additional diagnostic procedures. Properly managed first trimester monitoring lays the foundation for a safe pregnancy and reduces the risk of complications later in pregnancy.
Goals of first trimester monitoring
The main tasks of the first trimester:
- confirmation of intrauterine pregnancy and its viability;
- clarification of the gestational age;
- identification of risk factors;
- primary laboratory and infectious screening;
- assessment of the risk of fetal chromosomal abnormalities.
Initial visit to the obstetrician/gynecologist (7-9 weeks)
An initial visit to the doctor is recommended between 7 and 9 weeks of pregnancy. At this stage, the following is performed:
- collection of anamnesis (obstetric, gynecological, somatic, hereditary);
- assessment of risk factors (age, chronic diseases, previous pregnancies);
- general and gynecological examination;
- transvaginal ultrasound examination.
Transvaginal ultrasound allows:
- confirm the presence of intrauterine pregnancy;
- visualize the embryo and cardiac activity;
- rule out ectopic pregnancy;
- clarify the gestational age according to the CRL.
Laboratory tests of the first trimester
Laboratory tests performed in the first trimester of pregnancy are essential for assessing a woman's initial health status and early detection of factors that may affect the course of pregnancy. These tests are typically performed at 9–10 weeks of gestation and form the basic diagnostic basis for further monitoring. They help identify signs of anemia, inflammatory processes, immune system disorders, and possible infectious diseases that may be asymptomatic but pose a risk to the mother and fetus.
Particular attention is paid to immunohematological testing and serological screening in the first trimester. Blood typing and Rh factor determination, as well as an indirect Coombs test, are crucial for preventing Rh incompatibility and other immune complications. Serological tests are aimed at identifying infections that are potentially dangerous for fetal development and allow for timely determination of the need for follow-up or treatment. Conducting laboratory tests early in pregnancy allows for an individualized management plan and significantly reduces the risk of complications in subsequent trimesters.
Below is a table of the main blood tests performed in the first trimester.
Study Indication Target Clinical commentary
General blood analysis To all pregnant women Detection of anemia and inflammatory changes Physiological hemodilution is possible as early as the first trimester.
Blood type and Rh factor To all pregnant women Prevention of Rhesus incompatibility Mandatory in the absence of documented data
Indirect Coombs test To everyone, especially Rh(-) Detection of irregular antibodies Repeated dynamically with Rh-negative blood
Serology of syphilis To all pregnant women Prevention of intrauterine infection Mandatory screening
HIV To all pregnant women Prevention of vertical transmission Conducted with informed consent
Hepatitis B (HBsAg) To all pregnant women Detection of carriage Important for delivery tactics
Hepatitis C According to the readings Diagnosis of viral infection More common in risk groups
Toxoplasmosis In the absence of immunity Determining the risk of primary infection If IgG is negative, dynamic monitoring is required.
Combined prenatal screening of the first trimester
Combined screening is carried out at term 11–13 weeks of pregnancy and includes:
- ultrasound examination;
- biochemical blood test;
- Mathematical calculation of individual risk.
Ultrasonic markers
During the ultrasound the following are assessed:
- coccygeal-parietal length (CTL);
- nuchal translucency thickness (NTT);
- presence of the nasal bone;
- heart rate.
Biochemical markers
- free β-subunit of hCG;
- PAPP-A (pregnancy-associated plasma protein A).
Interpretation of results
| Risk level | Tactics |
|---|---|
| Short | Standard observation |
| Intermediate | NIPT recommended |
| High | Invasive diagnostics (chorionic villus biopsy/amniocentesis) |
Second trimester of pregnancy (14–28 weeks): morphological ultrasound, tests and prevention
The second trimester of pregnancy is an important stage for in-depth assessment of fetal development and clarification of early screening results. It is during this period, as a rule, that 19 and 21 weeksA morphological ultrasound examination is performed, which allows for a detailed assessment of the fetus's anatomy, the identification or exclusion of most structural congenital malformations, as well as indirect markers of chromosomal abnormalities.
Morphological ultrasound is of particular importance for determining the risk Down syndrome, since it is in the second trimester that it is possible to more accurately assess anatomical signs that either confirm a low risk or require further diagnostic clarification.
In addition to ultrasound diagnostics, laboratory tests are performed in the second trimester to detect anemia and metabolic disorders in the mother, including screening for gestational diabetes. This stage is also important for preventing complications in the second half of pregnancy and planning further follow-up care.
A comprehensive assessment of the mother and fetus in the second trimester allows for a high degree of reliability in confirming the normal development of pregnancy and promptly taking action if any abnormalities are detected.
Clinical tasks of the second trimester
The second trimester of pregnancy is considered the most stable period of gestation. For most women, symptoms of early toxicosis significantly diminish, general well-being improves, and active growth and differentiation of fetal organs and systems begins.
The main tasks of medical supervision in the second trimester:
- detailed assessment of the anatomical development of the fetus;
- detection of congenital malformations;
- diagnosis of metabolic disorders in the mother;
- prevention of complications in the second half of pregnancy;
- dynamic assessment of fetal growth and placental condition.
Second trimester ultrasound
Morphological ultrasound (19–21 weeks)
Morphological ultrasound is a key stage of antenatal care. It is performed optimally between 19 and 21 weeks of pregnancy and aims to provide a detailed assessment of fetal anatomy.
During the study, the following are sequentially assessed:
- central nervous system (brain, ventricles);
- face and neck area;
- spine;
- heart (four-chamber section, outflow tracts);
- chest organs;
- abdominal organs;
- kidneys and urinary tract;
- limbs;
- umbilical cord and placenta;
- amount of amniotic fluid.
Morphological ultrasound allows us to identify most structural developmental anomalies and determine the need for further in-depth examination.
Laboratory tests of the second trimester
The main planned analysis is carried out on time 24–28 weeks of pregnancy.
Study Indication Target Clinical commentary
General blood analysis To all pregnant women Anemia control The incidence of iron deficiency anemia increases in the second trimester
ferritin According to the readings Iron reserve assessment Preferred over whey iron
Blood glucose To all pregnant women Carbohydrate metabolism screening Held within the framework of O'Sullivan
Blood biochemistry According to the readings Evaluation of liver and kidney function Especially with a history of gestosis
Screening for Gestational Diabetes
O'Sullivan test
The O'Sullivan test is a screening method for diagnosing gestational diabetes and is performed on all pregnant women at term. 24–28 weeks, in the absence of high-risk factors.
Methodology:
- oral administration of a solution containing 50 g of glucose;
- measurement of venous blood glucose levels after 60 minutes.
The following result is considered pathological:
Glucose: ≥ 140 mg/dL, which corresponds 7.8 mmol/L,
and requires implementation diagnostic oral glucose tolerance test (OGTT).
Comment: mg/dL (mmol/L) - in Spanish clinical protocols, mg/dL is more often used for international understanding
It is permissible to indicate in mmol/l in brackets.
Oral glucose tolerance test (OGTT)
OGTT is performed in case of deviations in the O'Sullivan test or in the presence of risk factors.
The methodology includes:
- following a diet with sufficient carbohydrates for 3 days before the test;
- overnight fasting;
- intake of 75 g of glucose;
- blood sampling on an empty stomach, after 1 and 2 hours.
A diagnosis of gestational diabetes is made when threshold values are exceeded at at least one measurement point.
Preventive measures in the second trimester
Event Term Target Comment
Vaccination against whooping cough 27–36 weeks Prevention of neonatal whooping cough Recommended for all pregnant women
Anti-Rhesus immunoglobulin Week 28 Prevention of Rh sensitization Only for Rh(-) pregnant women
Third trimester of pregnancy (29–40 weeks): preparation for childbirth and monitoring of fetal condition
The third trimester of pregnancy is the final stage of antenatal care and is aimed at a comprehensive assessment of the woman's body's readiness for childbirth, as well as monitoring the condition and well-being of the fetus.
During this period, the main focus is on the dynamic assessment of fetal growth, placental function, the amount of amniotic fluid, and the position of the fetus, which allows for the timely detection of signs of placental insufficiency or other complications that may affect the delivery strategy.
In the third trimester, laboratory tests and instrumental control methods necessary for the safe management of labor are carried out, including an assessment of the hemostasis system and the functional state of the fetus.
Regular monitoring, ultrasound diagnostics, and cardiotocography help ensure the fetus is in satisfactory condition and determine the optimal time and method of delivery. Proper monitoring in the third trimester ensures maximum readiness for childbirth and helps reduce risks for both mother and unborn child.
Goals of third trimester surveillance
The third trimester is the final stage of pregnancy and requires more frequent medical monitoring.
Main tasks:
- assessment of the mother's body's readiness for childbirth;
- monitoring the growth and condition of the fetus;
- identification of signs of placental insufficiency;
- prevention of intranatal complications;
- planning delivery tactics.
Laboratory tests for the third trimester (32–34 weeks)
Study Indication Target Clinical commentary
General blood analysis To all pregnant women Anemia and platelet control Important before childbirth
Coagulogram To all pregnant women Evaluation of the hemostasis system Mandatory when planning epidural anesthesia
Blood biochemistry According to the readings Diagnosis of complications If preeclampsia is suspected
Third trimester ultrasound (32–36 weeks)
Ultrasound allows us to assess:
- estimated fetal weight;
- intrauterine growth rate;
- amount of amniotic fluid;
- localization and maturity of the placenta;
- fetal presentation.
Screening for Streptococcus agalactiae
On time 35–37 weeks Vaginal-rectal culture is performed to detect group B streptococcus.
The aim of the study is to prevent early neonatal infection. If the test is positive, intravenous antibiotics are administered during labor.
Cardiotocography (CTG)
Cardiotocographic examination is usually carried out with 39th week of pregnancy.
CTG allows to evaluate:
- basal fetal heart rate;
- variability;
- presence of accelerations and decelerations;
- contractile activity of the uterus.
Conclusion
Comprehensive and consistent pregnancy monitoring in accordance with current clinical guidelines ensures a high level of safety for both mother and fetus. An individualized approach based on risk factor assessment and dynamic monitoring is key to successful pregnancy management.
An expanded pregnancy checklist by week
Below is a systematic checklist of examinations and medical procedures performed during low-risk pregnancies. This table can be used both as a guide by patients and as a convenient clinical tool by physicians.
Pregnancy period Survey / event Indication Target Comment
7–9 weeks First visit to the obstetrician-gynecologist To all pregnant women Confirmation of pregnancy Formation of an individual monitoring plan
7–9 weeks Transvaginal ultrasound To all pregnant women Confirmation of viability Exclusion of ectopic pregnancy
9–10 weeks Blood tests in the first trimester To all pregnant women Basic laboratory screening Includes serology and immunohematology
11–13 weeks First trimester ultrasound To all pregnant women Screening for chromosomal abnormalities Measuring TVP
11–13 weeks Combined screening To all pregnant women Trisomy risk assessment Combination of ultrasound and biochemistry
>10 weeks NIPT According to the readings High-precision genetic screening It is not diagnostic.
16–18 weeks Scheduled visit To all pregnant women Condition monitoring Assessment of blood pressure, weight, complaints
Weeks 19–21 Morphological ultrasound To all pregnant women Diagnosis of developmental defects The key stage of observation
24–28 weeks Second trimester analytics To all pregnant women Detection of anemia and gestational diabetes mellitus Includes O'Sullivan
24–28 weeks O'Sullivan test To all pregnant women Screening for GDM In case of deviation - OGTT
27–36 weeks Vaccination against whooping cough To all pregnant women Prevention of neonatal infections Recommended by WHO
28 weeks Anti-D immunoglobulin Rh(-) Prevention of sensitization Repeat after birth if necessary
32–34 weeks Third trimester analytics To all pregnant women Preparing for childbirth Includes coagulogram
32–36 weeks Ultrasound of the third trimester To all pregnant women Fetal growth assessment Placenta and amniotic fluid monitoring
35–37 weeks GBS screening To all pregnant women Prevention of neonatal sepsis Vaginal-rectal culture
>35 weeks Consultation with an anesthesiologist According to the readings Pain management planning Important in case of concomitant diseases
≥39 weeks CTG To all pregnant women Monitoring fetal well-being It is held regularly
Mandatory and extensive examinations during pregnancy
For ease of understanding, all examinations can be conditionally divided into mandatory and additional (extended).
Mandatory examinations
| Survey | Reason for obligation |
|---|---|
| General blood tests | Detection of anemia and inflammatory processes |
| Determination of blood group and Rh | Prevention of Rhesus incompatibility |
| Serological screening | Prevention of intrauterine infections |
| Ultrasound by trimester | Monitoring fetal development |
| Screening for GDM | Prevention of perinatal complications |
| GBS screening | Prevention of neonatal infection |
Extended examinations (as indicated)
| Survey | Indication |
|---|---|
| NIPT | Increased risk according to screening |
| Invasive diagnostics | High risk of chromosomal abnormalities |
| Advanced Biochemistry | Somatic pathology |
| Thyroid profile | Thyroid diseases |
| Vitamin D | Deficiency/Risk Factors |
Common clinical situations during pregnancy management
Anemia in pregnant women
Iron deficiency anemia is the most common complication of pregnancy. Its early detection and treatment can reduce the risk of preterm birth, fetal growth restriction, and postpartum complications.
Rh-negative pregnancy
Pregnant women with Rh-negative blood require special monitoring and prophylactic administration of anti-Rh immunoglobulin to prevent alloimmunization.
Gestational diabetes mellitus
GDM is associated with an increased risk of fetal macrosomia, birth trauma, and metabolic disorders in the newborn. Adequate screening and glycemic control are key elements of management.
Intrauterine growth retardation
If IGR is suspected, an in-depth ultrasound and Doppler examination is carried out with individual planning of delivery.
Summary and recommendations of the VALINTERMED clinic for patients
Regular visits to the doctor, recommended examinations, and adherence to medical recommendations can help ensure the safest possible pregnancy and a favorable birth outcome.
Pregnancy is a physiological process, but systematic medical monitoring makes it safe for both the mother and the unborn child.
Blood tests during pregnancy: norms, units of measurement and clinical interpretation
Clinical commentary from Dr. Korzhikov (family physician, VALINTERMED)
In my practice, I always draw the attention of my patients to the fact that laboratory parameters during pregnancy are assessed differently than outside of pregnancyMinor deviations from reference values do not always indicate pathology and should be interpreted solely in the context of the gestational age, clinical picture, and dynamics of the indicators.
Specialists must adhere to the principle of reasonable sufficiency: only those tests are prescribed that truly impact pregnancy management, and their results are explained to the patient in detail in understandable language.
Laboratory blood tests are a key tool for assessing the health of a pregnant woman and her fetus. Physiological changes occurring in the body during pregnancy require a special approach to interpreting test results and dynamic monitoring of parameters.
Main blood changes during pregnancy
During pregnancy the following are observed:
- physiological hemodilution due to an increase in plasma volume;
- relative decrease in hemoglobin;
- moderate leukocytosis;
- changes in the hemostasis system with a tendency towards hypercoagulation.
These changes are normal, but it is important to distinguish physiological processes from pathological conditions.
Complete blood count by trimester
Indicator 1st trimester Second trimester Third trimester Comment
Hemoglobin ≥11.0 g/dL (≥110 g/L) ≥10.5 g/dl (≥105 g/l) ≥11.0 g/dL (≥110 g/L) Physiological decline in the second trimester is acceptable
Hematocrit 33–42 % 32–40 % 33–41 % Take into account physiological hemodilution
Leukocytes ≤12×10⁹/l ≤15×10⁹/l ≤15×10⁹/l Physiological leukocytosis of pregnancy
Platelets ≥150×10⁹/l ≥150×10⁹/l ≥150×10⁹/l Management of gestational thrombocytopenia
Blood biochemistry tests
Biochemical tests are prescribed routinely or according to indications, especially in the presence of concomitant diseases or pregnancy complications.
Indicator Purpose of the study Clinical commentary
AST, ALT Liver function assessment U/L (U/L), growth requires exclusion of hepatopathy and preeclampsia
Creatinine Kidney function mg/dL (µmol/L); during pregnancy, values are physiologically lower
Uric acid Risk of preeclampsia mg/dL (μmol/L); growth requires dynamic monitoring
Albumen Protein metabolism g/dL (g/L); moderate decrease physiologically
Vitamins and microelements: what is really necessary
In recent years, there has been a trend toward expanded vitamin and microelement testing. However, not all of these tests are mandatory.
Indicator When is it appointed? Comment
ferritin Often The main marker of iron reserves
Vitamin D According to the readings Not included in routine screening
Vitamin B12 For anemia Important for vegetarianism
Folic acid Before and in the first trimester Prevention of neural tube defects
Infections during pregnancy: screening and tactics
Infectious diseases during pregnancy can pose a serious risk to the fetus, especially during primary infection.
TORCH-infections
Screening is aimed at identifying immunity to:
- toxoplasmosis;
- rubella;
- cytomegalovirus;
- herpes simplex virus.
Interpretation of serological results should be performed by a physician taking into account the clinical picture and the dynamics of antibody titers.
Sexually transmitted infections
All pregnant women are screened for syphilis, HIV, and viral hepatitis. Early diagnosis significantly reduces the risk of vertical transmission.
Frequently Asked Questions (FAQ)
Is it necessary to take all the tests if the pregnancy is going well?
Yes. Many pregnancy complications can remain asymptomatic for a long time and are only detected in the laboratory.
Are frequent blood tests dangerous for a child?
No. The amount of blood collected is minimal and does not pose a risk to the mother or fetus.
Is it possible to refuse certain examinations?
The patient has the right to refuse, but the decision must be informed and made after discussion with the doctor.
Closing remarks
Comprehensive pregnancy care is the result of collaboration between doctor and patient. Regular monitoring, recommended examinations, and trust in medical advice can significantly reduce risks and ensure the birth of a healthy baby.
Legal and ethical aspects of pregnancy management
Pregnancy care is carried out within the framework of current legislation and the principles of medical ethics. The obstetrician-gynecologist is obligated to inform the patient about the purposes, methods, and possible consequences of the examinations performed.
Informed consent
Before invasive procedures, genetic tests, and certain types of examinations, the patient must provide informed consent. This means that the woman:
- receives complete and understandable information;
- understands possible risks and alternatives;
- makes a decision voluntarily.
Right of refusal
The patient has the right to refuse any examination or intervention. The doctor's responsibility is to explain the possible medical consequences of such a refusal and record it in the medical records.
Lifestyle during pregnancy
A pregnant woman's lifestyle directly affects the course of pregnancy and the development of the fetus.
Physical activity
In uncomplicated pregnancies, regular moderate physical activity is recommended:
- walking;
- swimming;
- special programs for pregnant women.
Physical activity helps reduce the risk of gestational diabetes, excess weight gain and back pain.
Nutrition
A pregnant woman's diet should be balanced and varied:
- adequate protein intake;
- sources of iron and calcium;
- limiting simple carbohydrates.
Strict diets and fasting are contraindicated during pregnancy.
Work and rest
Most women can continue their professional activities unless there are medical contraindications. It is important to maintain a rest regimen and avoid excessive physical and emotional stress.
Preparing for childbirth
The last weeks of pregnancy
After the 36th week of pregnancy, the main focus is on preparing for childbirth:
- assessment of the readiness of the birth canal;
- position and presentation of the fetus;
- choice of delivery tactics.
Birth plan
Creating an individual birth plan allows the patient's preferences to be taken into account, while all decisions are made with medical safety in mind.
Pain relief during childbirth
Pain relief options are discussed in advance, often with the participation of an anesthesiologist. Epidural anesthesia is the most common and effective method of pain relief.
The Postpartum Period: A Brief Overview
Although the postpartum period formally extends beyond pregnancy, preparation for it begins even before childbirth.
Early postpartum period
In the first weeks after birth the following is carried out:
- control of uterine involution;
- blood loss assessment;
- breastfeeding support.
Follow-up visit with a doctor
A postnatal examination is recommended 6–8 weeks after delivery to assess the woman’s recovery.
Result
Modern pregnancy care at the clinic is based on an individualized approach, evidence-based medicine, and a partnership between doctor and patient. Compliance with recommended monitoring stages, examinations, and the woman's informed participation in the pregnancy process are key to a favorable outcome for both mother and child.
The text may be used for informational and educational purposes on the website of medical clinics with the consent of the author VALINTERMED
