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Case 4.1 – Pre-Conception Care

Category: Endocrine & Reproductive Systems | Discipline: Obstetrics & Gynaecology | Setting: General Practice

Case

Harpa Singh aged 38 years presents to your general practice. She is known to you as an insulin-dependant diabetic. She has recently married and is hoping to conceive. She asks how she should prepare for pregnancy and in view of her age what are the risks of a chromosomal abnormality.

Questions

1. Describe the factors you would discuss that help assess the risks for this pregnancy for Harpa and for her baby.

Preconception Counselling - Risks of Pregnancy to Patient and Foetus:

Individual Factors:

  • Age - at 38 years, increased risk of chromosomal abnormalities
  • Ethnic background - certain genetic conditions more common in specific populations
  • Family history - chromosomal or genetic disorders

Social Factors:

  • Partner and family support
  • Work situation
  • Access to health care

Health Behaviours:

  • Smoking status
  • Alcohol use
  • Recreational drug use

Psychological Factors:

  • Depression
  • Anxiety
  • Stress
  • History of abuse

Reproductive History:

  • Previous pregnancies and outcomes

Medical History:

  • Any ongoing medical problems (particularly her insulin-dependent diabetes)
  • Current medications and their safety in pregnancy

Vaccinations:

  • Particularly rubella and varicella zoster if seronegative
  • Diphtheria, tetanus, pertussis
  • Measles

Nutrition:

  • Vegetarian diet
  • History of malabsorption

Family History:

  • If high risk of chromosomal or genetic disorder, pre-pregnancy genetic testing and counselling may enable couple to consider relative merits of pre-implantation genetic diagnosis versus prenatal diagnosis in pregnancy
2. Outline the general advice and the particular advice you would give.

General Advice

Nutrition:

  • Preconception folic acid supplementation
  • Diet: meat and green vegetables for iron
  • 3 serves dairy products for 1000mg calcium
  • Measures to avoid listeria (avoid soft cheeses, deli meats, etc.)
  • Increased fluid intake and adequate fibre to avoid constipation
  • Supplement 150mcg iodine
  • Role of multivitamins

Drugs and Substances:

  • Quit program for smoking
  • Recommend avoid alcohol and recreational drugs

Sexual Health:

  • STI screen, hepatitis, HIV

Lifestyle:

  • Regular exercise
  • Weight control
  • Dental hygiene

Medication Review:

  • Review all current medications (e.g., anti-hypertensive, anti-epileptic, anti-depressant)

Expectations:

  • Reassure that conception may take up to one year
  • Record dates of period on a calendar
  • General outline of antenatal care and first trimester screening
  • Early pregnancy symptoms (nausea, breast tenderness, fatigue, urinary frequency)

Other Advice:

  • If she has a cat, avoid contact with its faeces (risk of toxoplasmosis)

Specific Advice for Harpa (Diabetes)

Risk to Baby:

  • Risk of foetal congenital abnormality is high (cardiac defects and neural tube abnormalities)

Diabetic Control:

  • Strict diabetic control essential for conception and pregnancy
  • Monitor HbA1C and keep in normal range
  • Insulin needs will increase through pregnancy
  • Refer to endocrinologist for reassessment of diabetes, renal and eye disease

High-Dose Folic Acid:

  • Folic acid 5mg (instead of usual 0.4mg) for one month pre-conception at least and until 12 weeks pregnant
  • 5mg indicated if: previous baby or family history of neural tube defect, diabetes mellitus, epilepsy, BMI > 30, or malabsorption
3. Outline the examination you would perform and list the investigations you would recommend.

Examination

  • Height and weight for BMI calculation
  • Blood pressure
  • Auscultation of heart and lung fields
  • Breast examination
  • Abdominal palpation
  • Check for lymphadenopathy
  • Check for thyroid swellings
  • Pelvic examination if relevant

Investigations

  • Cervical Screening test
  • Rubella and varicella serology
  • FBC (Full Blood Count)
  • Ferritin if vegetarian or heavy menses
  • Blood group
  • Vitamin D levels if appropriate
  • Genetic test if indicated
  • Urine analysis
4. Harpa is worried that at age 38 she is at increased risk to have a baby with an abnormality. Describe to her the current screening and diagnostic tests available.

Background Information:

  • 50% of babies with a chromosomal abnormality are born to women younger than 35
  • All pregnant women should receive counselling and be offered screening for chromosomal abnormalities (chromosomes 21, 18, 13)
  • Risk of Down's syndrome: 1 in 300 at age 35 and 1 in 100 at age 40

Screening Tests

Combined First Trimester Screen (11-13+6 weeks):

  • Incorporates maternal age, ultrasound measurement of foetal nuchal translucency, and maternal serum markers (Papp-A - Pregnancy-associated plasma protein A & betaHCG)
  • Generates an overall risk figure for trisomy 21
  • Sensitivity: 85%, Specificity: 95%, Positive Predictive Value: 7-10%

Cell-free DNA (cfDNA) NIPT - Non-Invasive Prenatal Test (\>10 weeks):

  • DNA from foetus found in maternal blood
  • May need repeat in obesity
  • Sensitivity: 99%, Specificity: 99%, Positive Predictive Value: 45%

Quadruple Test (15-20 weeks) - for late booking:

  • Maternal age + AFP + betaHCG + UE3 + inhibin A
  • Sensitivity: 75%, Specificity: 95%, Positive Predictive Value: 2-3%

Morphology Ultrasound (18 weeks):

  • Detailed anatomical survey
Investigation Value Gestation Sensitivity Specificity Positive Predictive
Combined first trimester
Mat age+NT+betaHCG+Papp-A		 11-13+6 weeks 85% 95% 7-10%
Quadruple Test (late booking)
Mat age+AFP+betaHCG+UE3+inhibin		 15-20 weeks 75% 95% 2-3%
Cell-free DNA screening (NIPT) >10 weeks 99% 99% 45%

Diagnostic Tests

All abnormal screening tests require confirmation.

Amniocentesis (from 15 weeks):

  • Foetal cells are cultured from amniotic fluid aspirated from uterus
  • Performed under ultrasound guidance
  • Before 14 weeks: increased risk of talipes

Chorionic Villus Sampling (CVS) (after 11 weeks):

  • Aspiration under ultrasound of chorionic villi for genetic testing
  • Before 11 weeks: risk of transverse limb reduction defects

Testing Methods:

  • Conventional (G-banded) Karyotyping - uses cultured foetal cells
  • Rapid aneuploidy tests - FISH (fluorescent in situ hybridization) - adjunct to above for rapid assessment
  • Chromosomal Microarray analysis - assess foetal genome if foetal abnormality detected at ultrasound
5. What are the current Australian recommendations for the use of alcohol and smoking in pregnancy?

Alcohol Recommendations

  • Excessive alcohol can damage foetal development
  • The minimum or threshold level at which alcohol begins to pose a significant threat to pregnancy is not known
  • Avoidance of alcohol in pregnancy is recommended

Smoking Recommendations

Risks of Smoking:

  • Increases risk of infertility
  • Increases risk of miscarriage
  • Increases risk of adverse events in pregnancy
  • Increases risk of respiratory disease in the baby
  • Increases risk of sudden infant death syndrome (SIDS)

Management:

  • Women should be screened for smoking
  • Given counselling and behavioural support
  • Provided with written information
  • Referral to QUIT programs
  • Nicotine replacement therapy is NOT recommended in pregnancy
6. How might your advice change if Harpa had epilepsy, hypertension, thyroid disease, or depression?

General Principles for Chronic Medical Conditions:

  • Some medications present increased risks for foetal abnormality or growth and need to be changed prior to conception
  • Always check in MIMS or with the respective specialist that the current medication is safe in pregnancy
  • Referral for pre-natal foeto-maternal review may be indicated

Epilepsy

  • High-dose folic acid 5mg (same as for diabetes)
  • Medication review essential - some anti-epileptic drugs (AEDs) are teratogenic (e.g., sodium valproate has highest risk)
  • Serum levels of anti-epileptic medications decline with increasing haemodilution of pregnancy
  • Serum levels need to be checked throughout pregnancy and dosage adjusted as indicated
  • Balance between seizure control and foetal safety
  • Referral to neurologist recommended

Hypertension

  • Review anti-hypertensive medications - some are contraindicated in pregnancy (e.g., ACE inhibitors, ARBs)
  • Switch to pregnancy-safe options (e.g., methyldopa, labetalol, nifedipine)
  • Increased risk of pre-eclampsia and other pregnancy complications
  • May need closer monitoring during pregnancy

Thyroid Disease

  • Optimal thyroid function crucial for pregnancy
  • Serum levels of thyroxine decline with increasing haemodilution of pregnancy
  • Serum levels need to be checked throughout pregnancy and dosage adjusted as indicated
  • Both hypothyroidism and hyperthyroidism can affect fertility and pregnancy outcomes
  • Aim for TSH in lower half of normal range before conception
  • May need to increase thyroxine dose by 25-30% in pregnancy

Depression

  • Review anti-depressant medications for safety in pregnancy
  • Balance between maternal mental health and foetal medication exposure
  • Most SSRIs considered relatively safe (though some concerns about paroxetine)
  • Untreated depression carries its own risks to mother and baby
  • May need referral to perinatal psychiatry service
  • Increased support and monitoring during pregnancy and postpartum period