12.1 Antenatal Care, Maternal Nutrition & Fetal Assessment

12.1 Antenatal Care, Maternal Nutrition & Fetal Assessment

Antenatal care (ANC) encompasses systemic, periodic medical supervision of women during pregnancy to ensure optimal maternal and fetal health outcomes. The primary objectives of antenatal care are the early identification and management of high-risk obstetric conditions, promotion of maternal nutritional well-being, prevention of vertical transmission of infections, and reduction of maternal and perinatal morbidity and mortality.

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1. Antenatal Visit Schedules & Models

Historically, the traditional schedule of antenatal visits comprised monthly visits up to 28 weeks of gestation, fortnightly visits from 28 to 36 weeks, and weekly visits from 36 weeks until delivery (totaling approximately 12–14 visits).

WHO Focused Antenatal Care (FANC) vs. 2016 Recommendations

• Traditional 4-Visit Minimum Model (WHO FANC):
  1. First Visit: < 12 weeks (Registration, baseline investigations, dating, folic acid initiation).
  2. Second Visit: 14–26 weeks (Screening for preeclampsia, fetal anomaly scan at 18–22 weeks, Td vaccination).
  3. Third Visit: 28–34 weeks (Screening for anemia, gestational diabetes, fetal growth assessment, Td second dose).
  4. Fourth Visit: 36–40 weeks (Assessment of fetal presentation, position, pelvis, and delivery planning).
• WHO 2016 Comprehensive Model: Recommends a minimum of 8 antenatal contacts (at 12, 20, 26, 30, 34, 36, 38, and 40 weeks) to significantly reduce perinatal mortality and improve maternal health satisfaction.
• Pradhan Mantri Surakshit Matritva Abhiyan (PMSMA): A national initiative in India providing fixed-day, free, comprehensive antenatal check-ups on the 9th of every month by obstetricians and specialists for pregnant women in their 2nd and 3rd trimesters.

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2. Clinical Estimation of Gestational Age & Symphysio-Fundal Height

Naegele's Rule for Expected Date of Delivery (EDD)

$\text{EDD} = \text{First Day of LMP} + 7 \text{ Days} + 9 \text{ Calendar Months}$ (Alternatively: LMP + 1 Year - 3 Months + 7 Days)

• Prerequisites: Valid only for women with regular 28-day menstrual cycles. If the cycle length is longer (e.g., 32 days), add the extra days (e.g., +11 days instead of +7 days).

Milestones of Fundal Height Examination

Palpation of the uterine fundus provides a rapid clinical estimate of fetal growth and gestational age:

Differential Diagnosis of 32 vs. 40 Weeks Fundal Height: Both present with fundal height at the midway point between umbilicus and xiphoid. At 40 weeks, the fetal head is engaged, the flanks are full, and the abdomen is prominent anteriorly. At 32 weeks, the fetal head is unengaged, flanks are empty, and the girth is smaller.

McDonald's Rule

From 20 to 36 weeks of gestation, the Symphysio-Fundal Height (SFH) measured in centimeters using a tape measure over the abdominal curve corresponds directly to the gestational age in weeks ($\pm 2\text{ cm}$).

$\text{Gestational Age (in Months)} = \frac{\text{SFH in cm} \times 2}{7}$ $\text{Gestational Age (in Weeks)} = \frac{\text{SFH in cm} \times 8}{7}$

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3. Maternal Nutrition, Micronutrients & Immunization

Nutritional Requirements in Pregnancy

• Caloric Intake: Additional +350 kcal/day during the 2nd and 3rd trimesters (ICMR guidelines).
• Protein Intake: Additional +23 g/day of protein.
• Weight Gain Goals: Normal BMI (18.5–24.9): 11.5–16 kg total weight gain. Underweight (<18.5): 12.5–18 kg. Overweight (25–29.9): 7–11.5 kg. Obese (≥30): 5–9 kg.

Micronutrient Supplementation Protocols

1. Folic Acid:
   • Standard Prophylaxis: 400 mcg (0.4 mg) daily starting periconceptionally (3 months before conception) through 12 weeks of gestation to reduce Neural Tube Defects (NTD) such as anencephaly and spina bifida by >70%.
   • High-Risk Dose: 5 mg daily for women with a prior child with NTD, maternal pre-gestational diabetes, or women taking anti-epileptic drugs (valproic acid, carbamazepine).
2. Iron & Folic Acid (IFA) under Anemia Mukt Bharat:
   • Prophylaxis: 60 mg elemental iron + 500 mcg folic acid daily for 180 days, starting from the 2nd trimester (14 weeks onwards).
3. Calcium & Vitamin D3:
   • Prophylaxis: 1000 mg (1 g) elemental calcium + 250–400 IU Vitamin D3 daily starting from 14 weeks onwards (given as two doses of 500 mg calcium). Iron and calcium supplements must never be ingested simultaneously, as calcium inhibits non-heme iron absorption.
4. Tetanus and Diphtheria (Td) Immunization:
   • Td-1: Early in pregnancy (as soon as registered).
   • Td-2: 4 weeks after Td-1.
   • Td Booster: Single dose if the woman received two doses of Td in a pregnancy within the preceding 3 years.

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4. Screening for Fetal Aneuploidies & Structural Anomalies

First-Trimester Combined Screening (11 to 13+6 Weeks)

• Ultrasound Marker: Nuchal Translucency (NT) thickness (normal < 3.0 mm). Increased NT (≥3.0 mm) is associated with Trisomy 21 (Down syndrome), Trisomy 18, Trisomy 13, Turner syndrome, and congenital heart defects.
• Serum Markers: Elevated free $\beta$-hCG + Decreased Pregnancy-Associated Plasma Protein A (PAPP-A).
• Detection Rate: ~85–90% for Down syndrome.

Second-Trimester Quadruple Marker Screening (15 to 20 Weeks)

Measures four maternal serum analytes to risk-stratify for chromosomal anomalies and neural tube defects:

Memory Aid for Down Syndrome (Trisomy 21): "HI is High" — HCG and Inhibin-A are elevated, while AFP and $uE_3$ are reduced.

Ultrasound Anomaly Scan (TIFFA / Level II Scan)

• Performed at 18–22 weeks (ideal: 18–20 weeks). Systematically evaluates fetal anatomical structures (soft tissue markers, heart cardiac four-chamber view, spine, brain ventricles, kidneys, limbs) and placenta location.

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5. Fetal Well-Being & Surveillance Protocols

Daily Fetal Movement Count (DFMC)

• Cardiff "Count to 10" Method: Patient counts fetal movements starting at 9:00 AM. A count of 10 movements within 12 hours indicates fetal well-being.
• Sadovsky Method: Patient counts movements for 1 hour after meals. At least 4 movements in 1 hour (or 10 movements over 3 post-meal hours) is reassuring.

Non-Stress Test (NST)

Cardiotocography (CTG) monitoring of fetal heart rate (FHR) acceleration in response to fetal movements over a 20–40 minute window:

• Reactive NST (Reassuring): Presence of $\ge 2$ FHR accelerations of at least 15 beats per minute (bpm) above baseline, lasting for at least 15 seconds within a 20-minute tracing (the 15 $\times$ 15 rule for $\ge 32$ weeks; for $<32$ weeks, the 10 $\times$ 10 rule applies).
• Non-Reactive NST: Absence of adequate accelerations over 40 minutes. Indicates potential fetal hypoxia or fetal sleep cycle; requires further testing via Biophysical Profile (BPP) or Contraction Stress Test (CST).

Fetal Biophysical Profile (BPP / Manning Score)

Combines NST with real-time ultrasound parameters. Evaluates 5 parameters scored as either 2 (normal) or 0 (abnormal), giving a total score out of 10:

1. Non-Stress Test: Reactive NST = 2; Non-reactive = 0.
2. Fetal Breathing Movements: $\ge 1$ episode of rhythmic breathing lasting $\ge 30$ seconds within 30 minutes = 2.
3. Gross Body Movements: $\ge 3$ discrete body or limb movements in 30 minutes = 2.
4. Fetal Tone: $\ge 1$ episode of active extension with return to flexion of fetal limbs or hand = 2.
5. Amniotic Fluid Volume: At least 1 pocket of amniotic fluid measuring $\ge 2\text{ cm}$ in two perpendicular planes (or Amniotic Fluid Index / AFI $> 5\text{ cm}$) = 2.

Pathophysiological Concept: Amniotic fluid volume reflects chronic placental functioning/hypoxia (decreased renal perfusion causes oligohydramnios). In contrast, FHR accelerations, breathing movements, body movements, and tone reflect acute fetal central nervous system status, compromised in that exact sequential order during acute hypoxia.