Summary

Pre-conception care is a form of preventive medicine. It aims to reduce the adverse outcomes of pregnancy. It consists of two components - risk assessment and intervention, and health promotion. Pre-conception care is achieved by taking a history, performing a physical examination and carrying out screening tests. In order for it to be effective, the service should be provided in the primary health sector to all women of reproductive age who are not sterilised.

摘要

孕前護理是預防醫學的一環，主要包括高危因素 評估、處理和懷孕期健康促進兩方面，通過詢問病史、身體檢查和篩選測驗來達到減少懷孕併發症或不 良妊娠的目標。最有效的方法是由前線基層醫生向所有未絕育的生育期婦女提供此項服務。

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Introduction

Pre-conception care (PCC) is a form of preventive medicine. It is a logical precursor to antenatal care, since by the time a woman consults her obstetrician, organogenesis has already occurred and the baby's full potential may have already been compromised. The aims of PCC is to identify and reduce reproductive risks before conception takes place. It is achieved through

(a) risk assessment followed by intervention if any, which may involve specialist referral, and
(b) health promotion advice and counselling.

Consultation

Like any other clinical consultation, a PCC consultation starts with history taking (Table 1).

Table 1: Important points in the history
	Age Occupation Pets in household Family history Gynaecological history Obstetric history Past health Drug history - including cosmetic and weight reduction drugs Social history Well prepared for parenthood?

Age

Age is important as risk of foetal chromosopathy increases with maternal age. Elderly mothers, generally taken as those at or above 35 years old by expected date of confinement, should attend antenatal clinic early so that a timely prenatal diagnosis can be offered. For those women approaching the age of 30, the issue of fertility awareness should also be raised, especially nowadays as many tend to get married and pregnant late.

Occupation

Some occupations may carry pregnancy risks, for example, young child carers and kindergarten teachers, for whom it may be reassuring to know that they are CMV antibody positive. Fortunately, in Hong Kong, less than 5% of the adult population do not have CMV antibodies.

Pets in household

Toxoplasma gondii is most commonly spread via cat's faeces. Although toxoplasmal infection is uncommon in our locality, when primary infection occurs just before a pregnancy, it can cause transplacental spread and carries the risk of significant foetal infection. Congenital malformations or foetal death may then result. Hand washing after handling cats and other domestic animals is advisable and the disposal of cat litter should be avoided before and during pregnancy.

Family history

Quite a commonly raised question by potential mothers is a family history of mental retardation. Mild mental retardation behaves as part of the normal distribution of intelligence as a polygenic trait. One or both of the parents are usually retarded and the intelligence of future children will be distributed around the mid-parental mean. Correspondingly, the risk of an intelligent couple having a future mildly retarded child is low. By contrast, in severe mental retardation, parental intelligence is usually normal and a sharp discontinuity is seen between family members who are affected and the normal ones. Specific causes are more likely to be found. Accurate recognition is essential.¹ Referral to genetic counselling is advisable. Similarly, a family history of genetic problems or congenital malformations is also an indication for referral. Referral should be made to the Clinical Genetic Service, Department of Health.

Gynaecological history

A history of unsuccessful pregnancy after unprotected sexual intercourse of more than two times per week, for more than one year constitutes subfertility and needs referral to a gynaecologist. Referral may be made earlier if there are obvious causes of infertility and if the woman is older. Semen analysis is an essential investigation and may reveal conditions that necessitate referral of the male partner to the Male Infertility Clinic.

Obstetric history

Bad obstetric history such as recurrent spontaneous miscarriages, mid-trimester miscarriage or foetal death needs special investigations to find out the cause if any, if these were not properly carried out before. Again, referral to an obstetrician is appropriate. Despite this the yield for detection of abnormalities is likely to be low and only minimal benefit may be obtained to guide subsequent pregnancies.

Past health

It is obvious that poor health adversely affects pregnancy, and vice versa. Patients with insulin dependent diabetes mellitus are a good example where PCC is beneficial. The diminishing sensitivity to insulin as pregnancy advances renders diabetic control more difficult. There is persuasive observational evidence to support the concept that poor control of blood glucose in very early pregnancy is associated with an increased risk of malformations.² Non-randomised studies report a consistently lower incidence of congenital malformations with a regime of tight control.³ Apart from general PCC, information on specific risks of diabetic pregnancy can be given and measures to decrease the incidence of congenital malformations can be instituted through achieving periconceptional euglycaemia.

A PCC consultation provides an opportunity to review the risks and benefits of discontinuing or altering treatment prior to pregnancy for women with epilepsy. The overall frequency of congenital malformations, including neurotube defects (NTD), in babies born to women with epilepsy is estimated at three times the background rate, that is, 6% and even 10% with three or more drugs in combination.⁴ It may be possible to try decreasing or stopping anticonvulsant treatment for women who have been seizure-free for two years. As will be discussed later, there is evidence that periconceptional folic acid supplement decreases the incidence of NTD. A higher dose of 4mg is probably more appropriate in view of the altered folate metabolism in epileptic patients on anticonvulsant.

Though the course of pregnancy is usually not affected by epilepsy, the effect of pregnancy on epilepsy may be predicted by the degree of control achieved prior to pregnancy: the longer an epileptic patient has been seizure free, the less likely she will have convulsions in pregnancy. Hence, it is advisable to embark on a pregnancy after the disease has been stable for some time.

Drug history

Herbal medicines are commonly taken by the local people. Since their exact constituents are usually not known, it may be advisable to avoid taking once a decision is made to get pregnant.

Cosmetic medicines are quite popular nowadays for our more-and-more aesthetically minded women in Hong Kong. A number of acne treatments available including local application treatments contain retinoic acid which is teratogenic - 25% of babies will be affected by congenital malformations when it is used in pregnancy.⁵ After long term use, clearance of the drug is reduced and teratogenic effects may still be seen for some time after stopping treatment. It is advisable that women should avoid pregnancy for one year even when retinoic acid treatment is stopped. Oral acne treatment, which may contain tetracycline, should also be used very cautiously. It is better to use benzoic acid and erythromycin for local and oral treatment respectively.

Body slimming is also very popular among women. Weight reduction drugs may be laxatives, diuretics, thyroxine or even centrally acting appetite suppressants and are not advisable for use in women planning to get pregnant. Correct attitude towards weight control through dietary measures and exercise should be cultivated.

Illicit drug use is not rare among young women. Abused drugs not only pose a hazard to their health but also adversely affect the pregnancy outcome. For instance, heroin and cocaine may cause foetal growth restriction and their sudden abstinence in pregnancy may lead to foetal death.⁶

Social history

Last, but not the least, in the history, is the psychological and financial support the woman is having. Perhaps the most important question to ask is whether she is well prepared for parenthood.

Physical examination

History taking is followed by physical examination (Table 2). Weight and height are used to calculate Body Mass Index (BMI) which is normally between 19 to 25 kg/m² for women. Observational data revealed that those with a high BMI had an increased risk of delivering a macrosomic baby and of undergoing operative delivery, whereas a low BMI is associated with an increased risk of low birth weight babies and perinatal morbidities.^7,8 Thus, a normal BMI is encouraged.

General examination should also include inspection of teeth and oral cavity as dental disease can progress rapidly in pregnancy, and palpation for any goiter since thyroid problems are common in women.

Blood pressure is a vital baseline measure while cardio-respiratory examination is only indicated for those with symptoms. Abdominal examination may occasionally reveal organomegaly and fibroids.

Breast examination is not indicated routinely but is advisable if a check has not been performed in the preceding two years. Sometimes, a breast mass may be detected and need to be referred to the breast specialist.

Pelvic examination should be done for relevant symptoms and a high vaginal swab should be taken if indicated clinically. In asymptomatic women, there is as yet no proof that eradication of bacterial vaginosis is of benefit even though it is implicated in late miscarriage and preterm labour. A Pap smear should be taken if it has not been done within two years. An abnormal Pap smear result may be better dealt with before embarking on a pregnancy.

Table 2: Important points in the physical examination
	Body mass index
	Teeth and oral cavity, any goiter?
	Blood pressure
	Breast examination if not done within last 2 years
	Pelvic examination and high vaginal swab if indicated
	Pap smear if not done within last 2 years

Screening tests

Screening tests are important because they detect risks that may not be already known to the women (Table 3).

Table 3: Screening tests
	Mean corpuscular volume (MCV)
	Rhesus factor
	Rubella immunity
	Hepatitis B carrier status
	For those at risk: venereal disease research laboratory (VDRL) test, human immunodeficiency virus (HIV) antibody test, swab(s) for Neisseria gonorrhoeae e.g. endocervical swab, ligase chain reaction test for Chlamydia trachomatis.

Mean corpuscular volume (MCV)

A MCV <80fl is generally taken as abnormal and may indicate thalassaemia carrier status which occurs in 8% of the Hong Kong population. A thalassaemia carrier couple has a 25% chance of having an offspring with thalassaemia major disease and therefore may need early prenatal diagnosis. Though the diagnosis of the carrier status may also be made in the antenatal setting, tragedies have happened where the MCV report is overlooked and, also sometimes, women may book late on the assumption that themselves are perfectly normal.

Rhesus factor

Though prevalence of Rhesus D negative is rare in our locality, knowing the status can be extremely helpful in the event of threatened miscarriage. In order to prevent Rhesus isoimmunisation, anti-D antibody prophylaxis should be given for vaginal bleeding in Rhesus negative individuals except where the foetus is viable and less than 12 weeks gestation.⁹

Rubella immunity

Susceptibility to Rubella infection may be surprisingly discovered even with a history of prior vaccination. Rubella antibody levels may drop with time and so it is probably advisable to check antibody status before each pregnancy. Pregnancy should be avoided for one month after vaccination.

Hepatitis B carrier status

The status may be checked and vaccination may be given for those at risk, for example, sero-negative women whose work involves exposure to blood or blood products, though neonatal immunisation and immunoprophylaxis can effectively decrease the vertical transmission. Afterall, Hepatitis B carriage rate is high here and carries with it potentially serious health hazards, like liver cirrhosis and hepatocellular carcinoma.

For those women at risk, the following tests may be performed as well:

Venereal disease research laboratory (VDRL) test

It is usually checked in the booking antenatal clinic and if it is found to be reactive, treatment (usually penicillin) is instituted in pregnancy. Erythromycin, which is used in case of penicillin allergy, is not regarded as complete treatment for the foetus and hence postnatal treatment may become necessary.¹⁰ Therefore, it is always advisable to have the VDRL status checked before pregnancy for women thought to be at risk.

Human immunodeficiency virus (HIV) antibody test

Nowadays, universal HIV screening is available for all pregnant women in Hong Kong. Knowing a positive status prior to attempting a pregnancy avoids difficult decisions and dilemmas in pregnancy, for example, whether to terminate or to continue with the pregnancy.

Neisseria gonorrhoeae

Swabs should be taken from the endocervix, and various other sites if indicated, for isolation of Neisseria gonorrhoeae since majority of the infected women are asymptomatic.

Chlamydia trachomatis

It may be conveniently screened by using the ligase chain reaction (LCR) test on the early morning urine. The test has a sensitivity of 96% and a specificity of 99%.¹¹

Health promotion advice

Today, many people, men and women alike, are very health conscious. They take a lot of propriety treatments to promote their health, like vitamins and even herbal medicine. As discussed before, herbal medicine is not advisable. Truly, excessive vitamins may also lead to problems, for example, vitamin A in high doses (25000iu) is teratogenic.¹² Perhaps, in order to stay healthy, it is better to have a balanced diet containing fresh and natural food. Healthy eating involves ensuring an adequate intake of essential nutrients and the avoidance of teratogens and food-borne infection.

Listeria monocytogenes is present in soiled vegetables, and sometimes in soft cheese, prepared salads and cool-chilled meat. It can cause serious foetal infection resulting in foetal death or handicap. So, food should be carefully cleaned and thoroughly cooked and consumed soon after preparation.¹³

At present, there is no evidence to support the use of vitamin or trace elements when planning a pregnancy. An exception is folic acid which has been shown to reduce the incidence of NTD affected pregnancies. The association between folic acid and neural tube closure is not clear - whether supplementation corrects some deficient metabolism or leads to beneficial effects at supraphysiological doses is uncertain. It is recommended that women should take folic acid 400mcg per day from the time they decide to become pregnant until the twelfth week of gestation.¹⁴ Folic acid tablets are recommended since folate rich foods may not effectively increase folate levels in red cells. An argument against folic acid supplementation is that it may aggravate the neuropathy due to unrecognised vitamin B12 deficiency. Fortunately, this risk is very small.

Consumption of more than 15 and 20 units alcohol per week has been associated with a reduction in birthweight and intellectual impairment in children, respectively. Though there is no conclusive evidence of adverse effects in either growth or IQ at lower levels of alcohol consumption, the advice to have no more than one standard drink per day (1 unit of alcohol approximately equals 8g of absolute alcohol which is equivalent to 1 small glass of wine or 1 single measure of spirits or pint of ordinary strength beer) seems valid for all women, whether planning to get pregnant or not.¹⁵

There is much evidence that cigarette smoking has harmful effects on the foetus and smoking remains one of the few potentially preventable factors which are associated with low birthweight, very preterm and perinatal death. Smoking cessation can be effective in increasing mean birthweight.¹⁶ In those who cannot stop smoking, reduction should be the goal for all prospective mothers.

For would-be mothers, random exposure to radiation should always be avoided. Diagnostic and similar low level irradiation does not significantly increase the risk to an individual's offspring.¹⁷

Provided there are no medical contraindications, it is recommended that women who are contemplating pregnancy should engage in a moderate level of exercise so that they can maintain cardiovascular and muscular fitness when they become pregnant. Unless advised otherwise, there need be no restriction of sexual activity for potential mothers. A summary of health promotion advice is given in Table 4.

Table 4: Health promotion advice
	Balanced diet - fresh, natural, clean and thoroughly cooked food
	Folic acid 400mcg daily
	No more than one standard drink of alcohol per day
	Quit, or at least, reduce smoking
	Moderate exercise
	No restrictions on sexual activity

Criticism of PCC

Evidence to support the impact of PCC on adverse perinatal outcome is poor. Few PCC programs have been evaluated by randomised controlled trials. For women in general, folic acid supplement and ascertainment of Rubella status are the only interventions of proven efficacy. However, with the probable benefits of PCC, we should be monitoring PCC with research instead of ignoring it. On the other hand we should avoid excessive emphasis and creating a public misconception that all problems can be prevented.

Moreover, it is said that those who proactively pay PCC visit, may not be the ones who need it most. In addition, there are always unplanned pregnancies. Unintended pregnancies may have more risk factors than intended ones. In order for PCC to be effective, the concept of PCC should be integrated into all clinical encounters where women are seen, like in a general practice consultation, annual checkup visit, premarital counselling session, contraception clinic and even in child immunisation centres.^18,19 Every sexually active woman in the reproductive age group should be offered PCC unless she has been sterilised.

Lastly, there are concerns about the cost involved in carrying out PCC. Though formal cost calculations are not available, it is estimated that the cost should not be high since no special high-powered investigations or procedures are required. Printed information pamphlets on the topic of PCC are definitely of help in reducing the time needed for counselling, which is the main part of the PCC service, by busy primary health care workers.

Conclusion

Pre-conception care should not only be available in a dedicated PCC clinic. It is a form of proactive health care. It should be integrated into the primary health service and be offered to every woman who may get pregnant in the future.

A PCC consists of two main components: risk assessment and intervention, and health promotion. Risk assessment and intervention are achieved through history taking, physical examination and screening tests. Medical history and drug history are particularly important while blood pressure should always be measured during physical examination. Rubella antibody and mean corpuscular volume tests should also be performed. Proper interventions, including counselling, institution or alteration of treatment and specialist referral, should be carried out. Important health promotion advice should include the taking of folic acid and stopping, or at least reducing, smoking.

Overall, though the effect of PCC may be modest, there is no excuse not to do our best. More research is needed in the continued evaluation of the PCC programme.

Key messages

1. Always have the concept of pre-conception care in mind for every woman of the reproductive age group who is not sterilised.
2. Particularly important is the past medical history and drug history. Blood pressure should be measured during physical examination. Test for Rubella antibody and the mean corpuscular volume should also be performed.
3. Folic acid 400mcg daily should be prescribed and smoking should be stopped or at least reduced whenever a pregnancy is planned and attempted.

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References