What investigations are recommended for pregnant women in India during the 1st trimester of Antenatal Care (ANC)?

First Trimester ANC Investigations in India

All pregnant women in India should undergo comprehensive first-trimester screening that includes hemoglobin assessment, blood pressure measurement, blood grouping and Rh typing, blood glucose testing, thyroid function tests, and screening for infections including HIV, hepatitis B, and syphilis, with additional consideration for aneuploidy screening based on available resources.

Essential Laboratory Investigations

Hematological Assessment

• Complete blood count with hemoglobin estimation is mandatory, as approximately 51% of pregnant women in the first trimester in India have anemia (Hb <11.0 g/dL), with iron deficiency present in 40% of cases 1
• Serum ferritin (inflammation-adjusted) should be measured to identify iron deficiency, as only 56% of anemic women have concurrent iron deficiency that would respond to supplementation 1
• Blood grouping and Rh typing must be performed to identify women requiring Rh immunoglobulin prophylaxis

Metabolic and Endocrine Screening

• Thyroid function tests (TSH and free T4) are essential, as thyroid disorders affect 27.3% of high-risk pregnancies in India, with hypothyroidism in 17.3% and hyperthyroidism in 10% 2
• The first trimester is critical for thyroid assessment since fetal thyroid hormone production begins only after 12 weeks of gestation 3
• Fasting blood glucose or HbA1c should be checked, as gestational diabetes affects 16.1% of high-risk pregnancies 2

Micronutrient Assessment

• Vitamin B12 levels should be measured, as 30% of pregnant women in India have vitamin B12 deficiency 1
• Urinary iodine excretion should be assessed where feasible, as iodine insufficiency affects 16.79% of pregnant women in early gestation 3
• Folate deficiency screening can be considered, though prevalence is low (0%) in some Indian populations 1

Infectious Disease Screening

• Hepatitis B surface antigen (HBsAg) testing is recommended as part of standard antenatal care 4
• HIV testing should be offered to all pregnant women 4
• Screening for syphilis and other sexually transmitted infections should be performed
• Consider cytomegalovirus screening in specific clinical contexts 4

Blood Pressure and Cardiovascular Assessment

• Mean arterial pressure (MAP) measurement is critical for pre-eclampsia risk assessment, particularly in the 11-14 week window 5
• Blood pressure should be measured on at least two occasions, 4 hours apart, to establish baseline values 5
• Women with chronic hypertension require closer monitoring throughout pregnancy 4

Aneuploidy Screening

Risk-Based Approach

• First-trimester combined screening (maternal age, nuchal translucency, PAPP-A, and beta-hCG) should be offered between 11-14 weeks where ultrasound facilities are available 5
• Cell-free DNA screening can be offered as a more sensitive option where cost permits 4
• Women with isolated soft markers on ultrasound (such as choroid plexus cysts) should receive counseling about trisomy 18 risk and options for noninvasive screening 4, 6

Pragmatic Considerations for Resource-Limited Settings

• Where full aneuploidy screening is unavailable, focus on detailed anatomical ultrasound assessment in the second trimester
• Maternal serum screening (quad screen) can be offered in the second trimester if first-trimester screening was not performed 4

Ultrasound Evaluation

• Dating ultrasound should be performed in the first trimester (ideally 11-14 weeks) to establish accurate gestational age
• Nuchal translucency measurement should be included where trained personnel are available for aneuploidy risk assessment 5
• Assessment of chorionicity and amnionicity is mandatory for multiple pregnancies 4

Pre-eclampsia Risk Stratification

High-risk women (risk ≥1 in 100) should be identified using the combined first-trimester test including maternal risk factors, MAP, placental growth factor (PLGF), and uterine artery pulsatility index (UTPI) between 11-14 weeks 5

Contingent Screening for Resource-Limited Settings

• Where PLGF and UTPI measurements are unavailable, screen all women with maternal risk factors plus MAP 5
• Reserve PLGF and UTPI measurements for the subgroup at intermediate risk based on maternal factors and MAP 5

Maternal Risk Factors to Document

• Advanced maternal age (>35 years)
• Nulliparity or previous pre-eclampsia
• Family history of pre-eclampsia
• Obesity (BMI >30 kg/m²)
• Chronic hypertension or renal disease
• Autoimmune conditions (systemic lupus erythematosus, antiphospholipid syndrome)
• Diabetes mellitus
• Use of assisted reproductive technologies 5

Prophylactic Interventions Based on First-Trimester Assessment

Aspirin Prophylaxis

• Women identified as high-risk for preterm pre-eclampsia should receive aspirin 150 mg daily at bedtime, starting between 11-14 weeks and continuing until 36 weeks of gestation 5
• Low-dose aspirin should not be prescribed universally to all pregnant women 5

Calcium Supplementation

• In women with dietary calcium intake <800 mg/day, provide either calcium replacement (≤1 g elemental calcium daily) or calcium supplementation (1.5-2 g elemental calcium daily) to reduce pre-eclampsia risk 5

Iron and Folic Acid Supplementation

• All pregnant women should receive iron-folic acid supplementation, though current coverage shows 99.4% receive supplements but only 83.9% report daily consumption 1
• Folic acid 0.4 mg daily should be started preconceptionally and continued through the first trimester; increase to 4-5 mg daily in obese or diabetic women 4

Common Pitfalls to Avoid

• Do not rely solely on maternal risk factors for pre-eclampsia screening without incorporating MAP measurement, as this approach has inadequate predictive value 5
• Avoid using capillary blood specimens alone for hemoglobin assessment, as they overestimate anemia prevalence (51.1% vs 37.5% with venous specimens) 1
• Do not assume all anemia is iron-deficiency anemia, as only 56% of anemic women have concurrent iron deficiency; measure ferritin to guide appropriate supplementation 1
• Do not perform invasive diagnostic testing (amniocentesis) solely for isolated soft markers like choroid plexus cysts when aneuploidy screening is negative 4, 6
• Do not delay thyroid assessment beyond the first trimester, as the fetal thyroid becomes functional after 12 weeks and early maternal thyroid insufficiency can affect neurodevelopment 3

Follow-up Monitoring Schedule

• Repeat hemoglobin assessment every trimester, with more frequent monitoring (every 3 months) in women with documented anemia or iron deficiency 4
• Women on iron supplementation should have serum ferritin and iron studies rechecked every 3 months 4
• Thyroid function should be monitored throughout pregnancy in women with thyroid disorders 2
• Blood pressure monitoring should continue at each antenatal visit, with increased frequency in high-risk women 5