Dating pregnancies and Antenatal care

Dating pregnancyDating is important:

● Premature delivery dictates intervention

● Late pregnancy dictates induction of labor

Can anyone remember the formula used to date a pregnancy using the LMP?

Naegele’s rule...

Naegele's rule is a standard way of calculating the due date for a pregnancy. The rule estimates the expected date of delivery (EDD) either by adding one year, subtracting three months, and adding seven days to the first day of a woman's LMP or adding 9 months and 7 days to the LMP. The result is approximately 280 days (40 weeks) from the start of the last menstrual period.

What are some of the other methods used for dating pregnancy?

Scanning...

Scan dates are more accurate than menstrual dates, if done before 22 weeks. This is because they look at the actual age of the foetus, rather than fertilization dates.

Dating scan takes place between 10-14 weeks.

Crown-rump length and biparietal diameter are always used during this scan, sometimes along with head circumference and femur length. Nuchal translucency may also be measured if testing for Down’s Syndrome.

Antenatal care

Who provides the care?

• Midwives and GPs should provide the care for women with an uncomplicated pregnancy.

• Small group of healthcare professionals for continuity and to make the woman feel comfortable with the frequency of antenatal appointments

• For a nulliparous woman with an uncomplicated pregnancy there will be a schedule of 10 appointments

• For a parous women there will be a schedule of 7 appointments

Green Notes

The women carry their own set of notes with them.

The notes include:- Preferences for birth- Scan details- Previous births - Medical history

Lifestyle advice in pregnancy

- Supplements - vitamin D, folic acid (1st 12 weeks), start multivitamin supplements

- Avoiding food acquired infections - no ripened soft cheese, unpasteurised milk, avoid raw or partially cooked eggs

- Avoid alcohol consumption - Inform about specific risks of smoking in pregnancy and

benefits of quitting at any stage

MCQs…

What immunoglobulin passes the placenta?

a. IgGb. IgEc. IgAd. IgM

When prescribing HRT, what is the most significant risk of prescribing an oestrogen-only preparation rather than a combined oestrogen-progestogen preparation?

• Increased risk of venous thromboembolism• Increased risk of ovarian cancer• Increased risk of endometrial cancer• Increased risk of breast cancer• Increased risk of colorectal cancer

Which four of the following are risk factors for pre-eclampsia?

• Multiparity• Advanced maternal age• Family history• Personal history of disorders characterised by microvascular

disease• Multiple pregnancy• Smoking

SAQs...What produces hCG before the placenta? What is its purpose?

Syncytiotrophoblast, within 6-7 days of fertilisation. Ensures continuation of corpus luteum.

How long is the corpeus luteum required for pregnancy and for what function, and what takes over after this time?

1st trimester to produce progesterone required for pregnancy. The placenta.

What is pre-eclamspia?

A medical condition characterized by high blood pressure and significant amounts of protein in the urine of a pregnant woman. If left untreated, it can develop into eclampsia, the life-threatening occurrence of seizures during pregnancy.

By diffusion – lipid soluble.Possible cause of Fetal Alcohol Syndrome in which the maternal (mis)use of alcohol leads to:

● a fetus of low weight ● with growth restriction (potentially with learning difficulties, head and facial abnormalities)

How does alcohol cross the placenta? What implications does this have for the development of a baby whose mother drinks significantly during pregnancy?

What effects would you expect maternal smoking to have upon the placenta? What effect may this have upon the baby?

May reduce placental blood flow and growth. Poorer fetal nutrition will reduce birth weight, by on average, 200g.

What can be transported through the placenta that can/will cause problems to the developing fetus ?

SmokeDrugs - cocaineAlcohol - Fetal alcohool syndromeInfectious agents - RubellaAntibodies - Rhesus Disease

Thank-you!

Any questions?

f.white@warwick.ac.ukannabel.fothergill@warwick.ac.uk