Obstetrics and Gynaecology
Maternal Changes and Antenatal Care
Physiological changes of pregnancy and antenatal care for MBBS, including the 8-visit schedule, supplements, vaccination and screening scans, mapped to NMC codes OG7 and OG8.
MedNext Academy | 3 min read
Maternal Changes and Antenatal Care
Physiological changes of pregnancy and antenatal care for MBBS, including the 8-visit schedule, supplements, vaccination and screening scans, mapped to NMC codes OG7 and OG8.
This chapter describes how the mother's body adapts to pregnancy and how routine antenatal care uses those changes to keep mother and foetus well. It covers cardiovascular, haematological and other physiological shifts, the schedule and content of antenatal visits, screening investigations, supplementation and vaccination, and identification of high-risk pregnancies.
High-yield: Maternal Changes and Antenatal Care
- Plasma volume rises more than red cell mass in pregnancy, producing a physiological dilutional anaemia with the lowest haemoglobin around 30 to 32 weeks.
- Cardiac output increases by about 30 to 50 percent, mostly by mid-pregnancy, and peaks further in labour.
- The Government of India recommends at least eight antenatal contacts, aligning with the WHO 2016 model for a positive pregnancy experience.
- Iron and folic acid supplementation and calcium supplementation are routine parts of Indian antenatal care.
- Tetanus toxoid or Td vaccination is given in pregnancy; live vaccines such as MMR are contraindicated.
- The symphysio-fundal height in centimetres roughly matches the gestational age in weeks between 20 and 36 weeks.
- The first-trimester dating scan and the anomaly scan at 18 to 20 weeks are the two key routine ultrasounds.
- Blood pressure and urine protein at every visit screen for pre-eclampsia; new hypertension after 20 weeks is significant.
- A fasting or oral glucose tolerance test screens for gestational diabetes, usually around 24 to 28 weeks.
- Weight gain of about 10 to 12 kilograms is expected in a normal singleton pregnancy of average build.
- Foetal movements are usually felt by the mother (quickening) around 18 to 20 weeks in a first pregnancy.
- Blood group and Rh typing identify Rh-negative women who may need anti-D prophylaxis.
- Progesterone-driven smooth muscle relaxation causes constipation, reflux and ureteric dilatation with a tendency to urinary infection.
- A high-risk pregnancy is identified at booking and monitored more intensively than a low-risk one.
Core antenatal care checklist
- **Visits:** At least 8 antenatal contacts (WHO 2016 and Government of India).
- **Supplements:** Iron and folic acid plus calcium; Td or tetanus toxoid vaccination.
- **Screening at each visit:** Blood pressure, urine protein, fundal height and foetal heart.
- **Key scans and tests:** Dating scan, 18 to 20 week anomaly scan, glucose screen at 24 to 28 weeks.
NMC competencies in this chapter
- **OG7.1:** Maternal physiological changes in pregnancy
- **OG8.1:** Objectives of antenatal care, gestational age assessment and high-risk screening
- **OG8.3:** Obstetrical examination and clinical monitoring of maternal and foetal wellbeing
- **OG8.6:** Nutrition counselling in pregnancy
- **OG8.7:** Vaccination in pregnancy
- **OG8.8:** Antenatal investigations and ultrasound in initial assessment and monitoring
Frequently Asked Questions
Why do pregnant women develop physiological anaemia?
Plasma volume expands more than red cell mass, so the haemoglobin concentration falls by dilution, typically reaching its lowest point around 30 to 32 weeks. It is not true iron-deficiency anaemia.
How many antenatal visits are recommended?
At least eight antenatal contacts, in line with the WHO 2016 model and Government of India guidance, replacing the older four-visit schedule.
Which vaccines are given and avoided in pregnancy?
Tetanus toxoid or Td is given routinely and inactivated vaccines are safe. Live vaccines such as MMR and varicella are avoided during pregnancy.
How does the fundal height help in exams?
Between 20 and 36 weeks the symphysio-fundal height in centimetres approximates the gestational age in weeks, a simple bedside check often asked in clinical vivas.
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