An auxiliary nurse and midwife (ANM), Rajasthan, India
© 2009 UNFPA/RN Mittal, India, Courtesy of Photoshare
While the primary objective of pre-natal care is to reduce maternal and fetal morbidity and mortality, it is also a unique opportunity to see women regularly and impact their health long term.
Prenatal care includes education, preventive health care, and identification and mitigation of risks to mother and child. Prenatal care can be provided by a number of individuals, including family doctor, nurse practitioner, obstetrician, midwife, or a combination of these.
It is important to have discussions about pregnancy during health visits. Topics should include nutrition, folic acid supplementation, substance use, and violence and abuse. Where available, all women in preconception and early conception periods should receive 0.4-0.8 mg folic acid starting three months before conception to prevent neural tube defects, while intermediate- or high-risk women (epilepsy, insulin-dependent diabetes, obesity, family history of neural tube defect, high-risk ethnic group) should receive 4-5 mg daily. Folic acid should be continued for 3 months post-partum. Women should be advised to avoid smoking, alcohol, and illegal drug use. A history of rubella and varicella infection or vaccination should be evaluated, with titres or immunization potentially required. Chronic health conditions such as diabetes, asthma, hypertension, heart disease, kidney disease, or depression should be optimized.
Signs of pregnancy include absence of menstrual period, breast tenderness and fullness, fatigue, nausea, and urinary frequency.
Biochemical testing is done by detecting the beta subunit of the human chorionic gonadotropin (hCG) in urine or blood. Home testing has a sensitivity of 75%, while clinical laboratory testing has a sensitivity between 97-100% for both blood and urine.
Blood tests are typically positive 9 days post-conception, while urine tests are usually positive 14 days post-conception. False-negative results usually follow testing too close to ovulation.
The initial visit should occur within 12 weeks of the LMP, or earlier if the pregnancy is higher risk. It includes a complete history, physical examination, appropriate lab investigations, and counselling.
Gestational age is important to determine overdue status, for planning the birth and identifying the proper windows for screening. There are various ways of determining gestational age.
An estimated date of delivery, or gestational age, can be determined by Nagele's Rule:
From the date (first day) of the LMP, add 7 days and subtract 3 months from women with 28-day cycles. Alternatively, add 9 months and 7 days to the LMP.
Cycle regularity is important if using dates; ask the patient about regularity and contraception.
If the patient is unsure of their LMP, the most accurate method is the earliest done ultrasound, if available. Accuracy decreases as pregnancy proceeds.
Mechanisms and accuracy of ultrasound testing includes:
Other means of assessing gestational age include:
Begin with personal and demographic information to learn more about the patient as a person. Following this, proceed with:
History of current pregnancy
Past obstetrical history
gravida: number of pregnancies
parity: number of deliveries over 20 weeks,
regardless of outcome (twins, triplets, etc = 1)
abortion: number of deliveries under 20 weeks;
can be spontaneous or therapeutic
Past medical history and review of systems (optimize treatments)
Immunizations and immunity, especially:
Family medical and genetic history
Physical exam is done to ensure current maternal health and predict any potential problems with the pregnancy.
Where available, referral to perinatal classes should be offered and arranged.
Counselling should cover the following topics:
Women should ideally have a pre-pregnancy weight of BMI <30; however, rates of obesity among women continue to increase worldwide. It is important to counsel women with regards to risks of obesity.
Given the above risks, it is important to prepare for poor outcomes before, during, and after labour.
Routine investigations often done during the prenatal period include:
Other inital tests include:
Urinanalysis is done, though dipsticks will miss up to 25% of asymptomatic bacteriuria (ASB). Urine culture should be done between 12-16 weeks, as this detects 80% of women with ASB during pregnancy. ASB occurs in 2-7% of pregnant women and can lead to pyelonephritis, low birth weight, and preterm delivery and therefore must be treated (Bachman et al, 1993).
A dating ultrasound should be carried out at 8-12 weeks gestation.
Ultrasound for anatomic survey and to confirm dates should be booked for 18-20 weeks. However, in obese women, this is better done at 20-22 weeks.
Subsequent visits should occur every 4-6 weeks until 28 weeks, every 2 weeks until 36 weeks, and every week thereafter.
Calculate gestational age. If gestational age estimated from the 1st trimester ultrasound is more than 5 days apart from the age calculated from the LMP, the due date should be changed to reflect the dates based on ultrasound. If the 2nd trimester ultrasound is off by 10 days, the dates should also be changed to reflect this assessment.
Inquire as to
If there is concern regarding mood disorders, the Edinburgh Postnatal Depression Scale is one of the most frequently used tools. It is a self-report questionnaire, translated into many languages. It is recommended to be used between 28-32 weeks.
Pelvic exam may be done to assess cervical dilation and effacement as delivery approaches.
educational needs include:
At each visit, urine dip for protein (kidney function) and glucose (gestational diabetes) should be carried out.
If significant leukocytes are seen on urinalysis, sending for urine culture may be helpful to rule out asymptomatic bacteuria (which must be treated).
Done at 24-26 weeks. Provide 50g oral glucose challenge test. If the screen is >7.8 mmol/L at one hour, proceed to the 2 hour 75g gestational OGTT.
Group B strep swabs of vagina and anus (first vagina, then anus). There is some debate about utility of universal screening, though is now recommended by Society of Obstetricians and Gynecologists of Canada at 35-37 weeks.