First Trimester ANC Investigations

Essential Laboratory Investigations

Blood grouping and Rh typing must be performed to identify women requiring Rh immunoglobulin prophylaxis, according to the Obesity Reviews guideline society 1

Hepatitis B surface antigen (HBsAg) testing is recommended as part of standard antenatal care by the Journal of Hepatology guideline society 2
HIV testing should be offered to all pregnant women, as recommended by the Journal of Hepatology guideline society 2
Screening for syphilis and other sexually transmitted infections should be performed, according to the Journal of Hepatology guideline society 2
Consider cytomegalovirus screening in specific clinical contexts, as suggested by the American Journal of Obstetrics and Gynecology guideline society 3

Women with chronic hypertension require closer monitoring throughout pregnancy, according to the Journal of Hepatology guideline society 2

Cell-free DNA screening can be offered as a more sensitive option where cost permits, as recommended by the American Journal of Obstetrics and Gynecology guideline society 3, 4
Women with isolated soft markers on ultrasound should receive counseling about trisomy 18 risk and options for noninvasive screening, according to the American Journal of Obstetrics and Gynecology guideline society 3

Dating ultrasound should be performed in the first trimester to establish accurate gestational age, as recommended by the American Journal of Obstetrics and Gynecology guideline society 5
Assessment of chorionicity and amnionicity is mandatory for multiple pregnancies, according to the American Journal of Obstetrics and Gynecology guideline society 5

Advanced maternal age (>35 years) is a maternal risk factor for pre-eclampsia, as identified by the Obesity Reviews guideline society 1
Obesity (BMI >30 kg/m²) is a maternal risk factor for pre-eclampsia, according to the Obesity Reviews guideline society 1
Diabetes mellitus is a maternal risk factor for pre-eclampsia, as identified by the Obesity Reviews guideline society 1

Folic acid 0.4 mg daily should be started preconceptionally and continued through the first trimester, as recommended by the Obesity Reviews guideline society 1, 6

Repeat hemoglobin assessment every trimester, with more frequent monitoring in women with documented anemia or iron deficiency, as recommended by the Obesity Reviews guideline society 1, 6
Women on iron supplementation should have serum ferritin and iron studies rechecked every 3 months, according to the Obesity Reviews guideline society 1, 6

The American College of Medical Genetics recommends first-trimester combined screening, which includes nuchal translucency measurement and biochemical markers, at 11-14 weeks gestation, achieving detection rates of approximately 85-92% for Down syndrome with false-positive rates of 1-5% 7, 8
The American College of Medical Genetics suggests that the 12-week visit represents the ideal timing for comprehensive aneuploidy screening, which directly impacts pregnancy outcomes through early detection of lethal chromosomal abnormalities and major structural defects 7, 8

First-trimester combined screening at 11-14 weeks achieves detection rates of approximately 85-92% for Down syndrome with false-positive rates of 1-5%, according to the American College of Medical Genetics 7, 8
The nuchal translucency measurement must be performed between 11 weeks 4 days and 13 weeks 6 days gestation, making the 12-week visit critical timing, as recommended by the American College of Obstetricians and Gynecologists 7, 9

The American College of Obstetricians and Gynecologists recommends Tdap vaccination in the third trimester, ideally between 27-36 weeks gestation, not at 12 weeks, to ensure optimal transplacental antibody transfer to provide passive immunity to the newborn against pertussis 10
The American Diabetes Association recommends gestational diabetes screening at 24-28 weeks gestation in the general population, not at 12 weeks, except for high-risk women who should undergo early diabetes screening to detect undiagnosed pre-existing type 2 diabetes 11

The American Heart Association recommends blood pressure measurement at every prenatal visit, including the 12-week visit, to identify high-risk factors for preeclampsia, such as chronic hypertension, diabetes, obesity, advanced maternal age, previous preeclampsia, renal disease, and autoimmune disease 12
The American College of Obstetricians and Gynecologists recommends initiating low-dose aspirin (75-81 mg daily) starting at 12 weeks to reduce preeclampsia risk in high-risk women 12

The American College of Obstetricians and Gynecologists recommends confirming folic acid supplementation (0.4 mg daily for standard risk, 5 mg daily for women with BMI ≥30 or diabetes) through the end of the first trimester 10
The American College of Obstetricians and Gynecologists suggests considering aspirin 75-180 mg daily from 12 weeks for preeclampsia prevention in obese women (BMI ≥35) 9