Provide pre-pregnancy and periconception care, including medical optimisation and risk reduction

In one line

Periconception care is the window — from roughly three months before conception through early embryogenesis — in which optimising a woman's medical conditions, medications, micronutrients and immunity changes the outcome of a pregnancy she does not yet have; its single defining principle is that the highest-yield obstetric interventions happen before the first antenatal visit, because by the time most women book, organogenesis is already complete.

Mechanism & pathophysiology

The biological case for preconception care rests on a timing mismatch that no amount of good antenatal care can overcome. Organogenesis is largely complete by the end of the eighth post-conceptional week — by ten weeks' gestation in menstrual dating. The structures most vulnerable to teratogenic insult are forming during the very weeks in which a pregnancy is typically unrecognised: the embryo is most susceptible to major structural malformation between roughly the third and eighth weeks after conception, the classic critical period. An intervention that begins at the booking visit at 10–14 weeks arrives after the developmental decisions it could have influenced have already been made.

The neural tube is the cleanest illustration. The neural tube closes by about day 26–28 after conception — before a missed period is confirmed in many women, and well before a first antenatal contact. Folate supplementation cannot reverse a closure that has already failed; it can only support the closure if the substrate is present during the closure. This is why "start folic acid when you find out you are pregnant" is biologically too late for neural-tube defect (NTD) prevention, and why preconception, not antenatal, supplementation is the evidence-based recommendation.

Folate's mechanism is in one-carbon metabolism. Folate (as 5-methyltetrahydrofolate) donates methyl groups for the remethylation of homocysteine to methionine and for de-novo synthesis of purines and thymidylate — the nucleotide building blocks of DNA. Rapidly dividing tissue, such as the closing neural folds, has a steep demand for this one-carbon flux. Methionine in turn feeds S-adenosylmethionine, the universal methyl donor for the DNA and histone methylation that governs which genes are expressed in the early embryo — so a folate-deficient periconception state is both a nucleotide-supply problem and an epigenetic one, which is part of why folate's reach extends beyond NTDs to a smaller reduction in some congenital heart and orofacial-cleft defects. Where folate is limiting, or where a genetic or pharmacological block raises that demand (anti-folate anticonvulsants, the methylenetetrahydrofolate reductase polymorphisms that reduce conversion to the active form, the hyperglycaemic milieu of poorly controlled diabetes), the failure rate of neural-tube closure rises. Supplemental folic acid raises tissue folate above the threshold at which closure becomes substrate-limited. The mechanism is preventive saturation, not repair, which is exactly why the dose has to be on board before day 28 — and why fortification, which keeps the whole population's red-cell folate elevated continuously, protects pregnancies that were never planned.

A wider mechanistic frame sits behind all of this. The developmental origins of health and disease hypothesis — the Barker work on fetal programming — holds that the intrauterine environment, set in motion by maternal nutrition and metabolic state from conception onward, programmes the offspring's later risk of cardiometabolic disease. Maternal hyperglycaemia, obesity, undernutrition and micronutrient deficiency at the point of conception are not neutral background; they are early inputs into a developmental trajectory. The periconception window is therefore not only about avoiding discrete catastrophes (an NTD, a cardiac defect) but about the metabolic setting in which the conceptus begins. That reframes preconception care from a checklist of single risks into an attempt to start the pregnancy in the best possible physiological state.

The corollary for diabetes makes the point quantitatively. Maternal hyperglycaemia in the first trimester is teratogenic in a dose-dependent way: a first-trimester HbA1c above 10% (86 mmol/mol) carries congenital-malformation rates reported around 20–30%, against a background population rate of 2–3%. Glucose crosses the placenta freely and, in the unregulated embryonic milieu, drives oxidative stress and disordered gene expression in the very tissues differentiating during weeks three to eight; the malformations that result — cardiac outflow lesions, neural-tube defects, the near-pathognomonic caudal regression sequence — track the period of organogenesis precisely. The risk is graded, not all-or-nothing: every increment of HbA1c toward normal lowers it, which is why "near target" still helps when "at target" is not achievable. Glycaemic optimisation before conception is the only intervention that addresses this, because by booking the damage, if any, is done.

The same logic generalises to every teratogen and to maternal weight. A drug's danger depends on whether the woman is taking it during the window of susceptibility of the organ it affects, and most teratogenic exposures that matter occur before pregnancy is recognised — which is the unifying argument of the whole topic. Obesity raises the conceptus's risk of NTDs and cardiac defects (in part through relative folate insufficiency and the metabolic environment), and underweight and micronutrient deficiency shift the developmental programme in the opposite, growth-restricted direction. None of these is correctable from the booking visit; all are addressable from a preconception one.

Assessment

A structured preconception assessment is a systematic search for the modifiable risks that, left to the booking visit, would be too late to modify. It is opportunistic in most South African settings — taken at a contraception consultation, a chronic-disease visit, a postnatal review, a termination-of-pregnancy contact — because dedicated preconception clinics are scarce and the unplanned-pregnancy rate is high.

Medical conditions — the optimisation list.

• Diabetes (pre-existing type 1 or type 2): the highest-yield single condition. Assess glycaemic control (HbA1c), end-organ status (retinopathy, nephropathy with albumin:creatinine ratio and eGFR, neuropathy), and current therapy. A woman on an oral agent other than metformin, or on an ACE-inhibitor/ARB for nephroprotection, needs a planned medication change. The target is preconception HbA1c <48 mmol/mol (6.5%) where achievable without disabling hypoglycaemia, and a strong recommendation to defer pregnancy while HbA1c is >86 mmol/mol (10%). This builds on diabetes-in-pregnancy.
• Chronic hypertension: identify and stop teratogenic antihypertensives. ACE-inhibitors and ARBs must be switched off — first-trimester exposure is associated with congenital malformation, and second/third-trimester exposure causes the fetopathy syndrome (renal failure, oligohydramnios, pulmonary hypoplasia, skull hypoplasia). Substitute a pregnancy-compatible agent before conception. See hypertension-in-pregnancy-antihypertensives.
• Epilepsy: review the anticonvulsant. Sodium valproate carries a major-malformation rate around 10% and a 30–40% rate of neurodevelopmental disorder, and is contraindicated in women of childbearing potential outside a pregnancy-prevention programme; switching to a lower-risk agent (and to monotherapy at the lowest effective dose) is a preconception, not antenatal, task, because the change must be stable and seizure-controlled before conception. Anti-folate anticonvulsants also dictate high-dose folate.
• Thyroid disease: confirm euthyroidism; hypothyroid women typically need a dose increase early in pregnancy and benefit from optimisation beforehand. See thyroid-disorders-in-pregnancy.
• Cardiac disease: the consultation in which a woman with significant structural or pulmonary-vascular disease is counselled about the maternal risk of pregnancy — including the conditions in which pregnancy is contraindicated — belongs preconception, not at booking. Risk-stratify (the modified WHO classification) and refer. See cardiac-disease-in-pregnancy.
• Renal disease: baseline eGFR, proteinuria and blood pressure stratify the risk of accelerated decline and of superimposed pre-eclampsia, and frame the conversation about timing. See renal-disease-in-pregnancy.
• Autoimmune disease / antiphospholipid syndrome: disease should be quiescent on pregnancy-compatible therapy before conception (switching off methotrexate and mycophenolate, which are teratogenic); APS dictates a planned aspirin ± heparin regimen. See sle-and-antiphospholipid-syndrome.
• Mental health: screen for existing illness — including a history of bipolar disorder or postpartum psychosis, which carries a high recurrence risk in a future puerperium and reshapes the whole peripartum plan — and review psychotropics for the risk/benefit of continuation. The reflex to stop every psychotropic before pregnancy is a trap: abrupt discontinuation of effective treatment risks relapse, and an unwell mother is itself an adverse exposure for the pregnancy. The preconception task is a deliberate medication review (for example, the specific concerns around sodium valproate as a mood stabiliser and around certain agents in the first trimester) and a shared decision about continuing, switching or adjusting, made before conception when there is time to monitor the change.
• Haemoglobinopathy: in at-risk populations, identify carriers — this is the entry point to couple/genetic counselling.

Reproductive and obstetric history. Prior NTD, prior congenital anomaly, recurrent miscarriage, prior pre-eclampsia or preterm birth, prior stillbirth, prior gestational diabetes — each redirects the plan (a prior NTD mandates 5 mg folate; recurrent loss prompts a defined work-up). Cervical surgery and prior caesarean inform later planning.

Genetic, carrier and consanguinity assessment. A three-generation family history identifies inherited disease, a prior child with a genetic or chromosomal condition, recurrent loss suggestive of a balanced translocation, and the patterns that warrant referral to clinical genetics. Consanguinity raises the risk of autosomal-recessive conditions and warrants counselling and, where relevant, carrier testing — the value of doing this preconception is that a couple identified as both carriers of a serious recessive condition then has the full range of reproductive options (prenatal diagnosis, donor gametes, pre-implantation genetic testing, the informed choice to proceed) available before, not during, a pregnancy. Ethnicity-directed carrier screening (thalassaemia, sickle cell) and a discussion of available aneuploidy and structural screening belong here, framed by what is actually accessible in the local service. The preconception window is also when advancing maternal (and paternal) age and its aneuploidy implications can be discussed without time pressure.

Infections and immunity. Test for and address HIV (status, and if positive, ART optimisation and viral suppression before conception — preconception PVT care, see below), syphilis, hepatitis B (and counsel on neonatal vaccination/immunoglobulin planning), and check rubella and varicella immunity so that susceptible women can be vaccinated before pregnancy.

Lifestyle and exposures. Quantify BMI (both extremes carry risk; obesity raises NTD, gestational diabetes, pre-eclampsia and operative-delivery risk), smoking, alcohol (counsel total abstinence — there is no established safe threshold for fetal alcohol spectrum disorder), recreational substances, and occupational or environmental exposures.

Medications and teratogens. A deliberate review of every prescription, over-the-counter and traditional medicine the woman takes, against pregnancy safety — applying the principles of teratogenesis (timing relative to organogenesis, dose, and the limits of the old categorical safety labels). The principle is to make the switch to a pregnancy-compatible regimen before conception, never to discover a teratogen at booking.

Immunisation status. Beyond rubella/varicella, ensure routine immunisations are current; live vaccines have to be given preconception because they are contraindicated in pregnancy. Hepatitis B susceptibility (in a woman not already immune or infected) can be addressed with an inactivated vaccine that is not pregnancy-restricted, but is cleaner done in advance.

The interpretive thread that runs through the whole assessment is that a preconception consultation is not a screening sweep for its own sake — each finding is only useful if it changes an action that can only be taken before conception. A raised HbA1c means defer-and-optimise; a teratogenic drug means switch-with-lead-time; non-immunity to rubella means vaccinate-then-wait-a-month; a prior NTD or anticonvulsant means high-dose folate; a positive HIV status means suppress-the-virus-before-conceiving; consanguinity means counsel-and-test. The skill being examined is reading each result back to the single preconception action it mandates, not producing the list.

Management

Preconception management follows the assessment directly: optimise what is treatable, switch what is teratogenic, supplement what is deficient, immunise what is susceptible, and counsel on what is behavioural — all before conception, because that is the only point at which most of it works.

Folic acid — the dose decision. Every woman planning or capable of pregnancy should take folic acid; the only real decision is which dose.

The standard 0.4 mg dose reflects the trial evidence for first-occurrence prevention; the 5 mg dose reflects the higher absolute risk in the listed groups. The most secure indications for 5 mg are a prior NTD pregnancy, pre-existing diabetes, and folate-interacting anticonvulsants. The weakest is isolated obesity, where the direct supporting evidence is thin — a point taken up in the controversy.

Optimising chronic disease and switching teratogenic drugs — before conception. Bring HbA1c to target in diabetes; achieve disease quiescence on a pregnancy-compatible regimen in autoimmune disease; reach euthyroidism. The diabetes consultation is the template for the rest: optimise glycaemia toward the target, establish first-trimester-safe therapy, treat retinopathy that could progress in pregnancy, assess renal function, and add high-dose folate — a bundle of actions, all preconception, that between them account for most of the avoidable excess malformation and loss in diabetic pregnancy. Make the teratogen switches deliberately and with enough lead time to confirm the new regimen controls the disease, because a switch that destabilises an epileptic or psychiatric illness trades one harm for another:

Immunisation. Vaccinate susceptible women against rubella and varicella preconception. Because MMR and varicella are live attenuated vaccines, they are contraindicated in pregnancy and must be given at least one month (the conventional 28-day interval) before conception, with contraception in that interval. Inadvertent administration in early pregnancy is not, on current evidence, grounds for termination — no congenital rubella syndrome has been attributed to the vaccine strain — but it is avoided by checking immunity and timing the vaccine preconception.

Lifestyle modification. Smoking cessation, alcohol abstinence, weight optimisation toward a healthier BMI before conception, a folate-replete diet, and review of caffeine and supplements. These are slow to act, which is the argument for starting them preconception rather than at booking. Alcohol counselling is explicit and unhedged: there is no established safe threshold, the spectrum of fetal alcohol harm includes the irreversible neurodevelopmental phenotype, and the only safe advice when planning pregnancy is abstinence. Weight optimisation is framed as a lead-time intervention — a meaningful change in BMI takes months, so it is started when a woman first signals intent to conceive, not deferred to a pregnancy that will already be established before the weight moves.

A useful way to hold the whole plan is the immediate → ongoing → long-term frame. Immediate (this consultation): start folic acid at the correct dose, stop or switch teratogens, check and act on rubella/varicella immunity and HIV status, give clear alcohol/smoking advice. Ongoing (the weeks to months before conception, ideally three): bring the chronic disease to target — HbA1c, blood pressure on a compatible agent, disease quiescence, euthyroidism — confirm the new drug regimen is effective and stable, and complete any vaccination interval. Long-term (into the pregnancy itself): hand over to antenatal care a woman who arrives already supplemented, already on safe drugs, already optimised, with a documented plan — so the booking visit confirms and continues rather than starts from scratch.

The South African reality. Dedicated preconception clinics are largely absent in the public sector, so preconception care here is opportunistic and every-contact: it is delivered at the family-planning visit, the chronic-disease clinic, the postnatal and the post-termination contact, not at a clinic dedicated to it. This matters because the unplanned-pregnancy rate is high, which structurally undermines a model that depends on a woman presenting before she conceives. The practical response is twofold: deliver the highest-impact interventions (folate, teratogen review, disease optimisation, immunity check) at every contact with a woman of reproductive age, and integrate preconception messaging into contraception care so that the same visit that prevents an unplanned pregnancy also prepares for a planned one. National maternity policy frames pre-pregnancy optimisation within this opportunistic model.

HIV preconception care (PVT). For a woman living with HIV who is planning pregnancy, the preconception task is to establish her on effective antiretroviral therapy and achieve viral suppression before conception — the most effective single step in prevention of vertical transmission (PVT), and one that also protects her own health and reduces the risk to a serostatus-discordant partner during conception. Where the partner is uninfected, safer-conception strategies (the positive partner virally suppressed, pre-exposure prophylaxis for the negative partner, timed conception) belong in this consultation. This is the preconception entry point into the SA PVT pathway taken up in advanced HIV-in-pregnancy management.

Guidelines compared

The major bodies agree on the spine of preconception care and diverge mostly on emphasis, the high-dose folate question, and the service model.

The clearest divergence is the 5 mg folate indication list, which varies internationally — most agree on prior NTD, diabetes and anti-folate anticonvulsants; obesity and the malabsorption conditions are where lists differ and the evidence is softer. The second is the service model: a dedicated preconception clinic (resource-rich) versus the every-contact opportunistic model (the realistic SA approach).

The evidence & the controversy

The foundation is unusually robust for a preventive intervention. The MRC Vitamin Study (1991) settled folate's role in recurrence: 4 mg folic acid periconceptionally cut NTD recurrence by 72% (RR 0.28) in women with a prior affected pregnancy, a result so clear the trial stopped early. The Czeizel and Dudás Hungarian RCT (1992) extended this to first occurrence, showing a periconceptional multivitamin containing 0.8 mg folic acid prevented first-occurrence NTDs. Together they convert "supplement folate" from plausible to proven, and they fix the timing: the benefit exists only when the folate is taken periconceptionally, through the closure window.

The live controversy is the 5 mg dose. Recent evidence reviews have questioned how much of the high-risk-group 5 mg recommendation rests on direct trial evidence versus consensus extrapolation. The trial-supported high-dose groups are essentially those with a mechanistically higher demand or a prior event — prior NTD, anti-folate anticonvulsants, and pre-existing diabetes. For obesity, the basis for 5 mg (rather than 0.4 mg) is weaker, and some guidance now holds that a raised BMI alone, without another risk factor, does not clearly require the higher dose. The defensible position is to state the dose, name the indication it rests on, and acknowledge where the evidence is consensus rather than trial — not to recite a single fixed list as though every entry were equally evidenced.

A second thread is the population versus individual approach. South Africa's mandatory fortification of maize meal and wheat flour with folic acid, introduced in October 2003, was followed by a roughly 30% fall in NTD birth prevalence — a population-level intervention that reaches the very women (with unplanned pregnancies, never seen preconception) whom individual supplementation misses. This is the structural argument: in a setting with a high unplanned-pregnancy rate, fortification does the work that a preconception clinic cannot, and individual supplementation layers on top for those who do plan. It reframes the consultant's role from prescriber of folate to advocate for the population programme that protects the patients who never reach the clinic.

The broader controversy is the developmental-origins claim itself. The Barker hypothesis is well supported for the association between early-life metabolic environment and later disease, but the causal weight of periconception-specific interventions on adult cardiometabolic outcomes — as opposed to the discrete and proven prevention of malformation — remains an area of active debate, and the honest framing distinguishes the proven (NTD prevention, malformation reduction with glycaemic control) from the plausible-but-unproven (long-range programming effects of preconception optimisation). The defensible stance is to act firmly on the proven and to present the programming rationale as a reasonable additional argument for optimisation, not as established fact.

A current thread that increasingly enters preconception discussion is environmental and endocrine-disrupting exposures — bisphenols, phthalates, certain pesticides and the broader chemical environment — proposed to affect fertility and early development. The evidence here is mostly observational and mechanistic rather than from interventional trials, and the appropriate consultant posture is to treat it as biologically plausible and worth pragmatic, low-cost advice (reducing avoidable exposures, occupational risk assessment) while being explicit that the causal and dose-response data do not support alarmism or specific testing. It is a genuine area of contemporary interest precisely because it is contested; presenting it as settled in either direction is the error. The same calibrated stance applies to the periodic claims about chemicals in everyday products: weigh the evidence, advise proportionately, and label the uncertain as uncertain.

The structural problem deserves its own emphasis because it is where the SA answer differs most from the textbook one. A preconception model that depends on a woman presenting before she is pregnant is structurally defeated by a high unplanned-pregnancy rate: the women at highest risk — the poorly controlled diabetic, the woman on valproate, the woman with untreated HIV — are precisely those least likely to attend a planning consultation. The consultant response is not to perfect a clinic few attend, but to push the highest-impact interventions upstream into every contact a reproductive-age woman has with the health system (contraception, chronic-disease, postnatal, post-termination visits), to default to pregnancy-compatible prescribing in any woman who could conceive, and to support the population measures — fortification above all — that protect the unplanned pregnancy. Designing care around the pregnancy a woman will have rather than the one she plans is the realistic frame.

Landmark trials & key evidence

The first two rows are the citable spine of any NTD-prevention answer. The fortification row is the SA-specific datum that distinguishes a consultant's answer in this setting from a generic one.

Exam traps & red flags

• Starting folate at booking. Folate begun when pregnancy is confirmed misses the closure window (day 26–28); for NTD prevention the dose must be taken periconceptionally. This is the central conceptual error of the topic.
• Wrong folate dose for the risk. Giving 0.4 mg to a woman with a prior NTD, diabetes or on valproate is undertreatment; she needs 5 mg. Conversely, defaulting every raised-BMI woman to 5 mg overstates an indication the evidence does not firmly support.
• Leaving an ACE-inhibitor/ARB running into pregnancy. It must be switched off preconception; discovering it at booking has already risked first-trimester exposure.
• Continuing valproate in a woman who may conceive. A ~10% malformation rate and 30–40% neurodevelopmental-disorder rate make this a preconception switch, inside a pregnancy-prevention framework, not an antenatal afterthought.
• Giving a live vaccine without checking pregnancy status / timing. MMR and varicella are contraindicated in pregnancy and must precede conception by at least a month — but inadvertent administration is not itself an indication for termination.
• Deferring diabetes optimisation to the antenatal clinic. First-trimester hyperglycaemia is teratogenic; the malformation risk is set before booking, so glycaemic control is a preconception target (HbA1c <48 mmol/mol; defer pregnancy if >86 mmol/mol).
• Treating preconception care as a clinic that does not exist. In SA the realistic model is every-contact and opportunistic; waiting for a dedicated preconception visit means most women are never reached, given the high unplanned-pregnancy rate.
• Missing HIV preconception optimisation. For a woman living with HIV planning pregnancy, viral suppression before conception is the highest-yield PVT step and a safer-conception conversation point — not something to begin only at booking.
• Forgetting consanguinity and carrier risk. A family history and consanguinity assessment is part of the consultation; omitting it misses inherited-disease counselling that can only usefully happen before conception.

Evidence anchors

• MRC Vitamin Study — prevention of neural tube defects, Lancet 1991
• Czeizel & Dudás — prevention of first occurrence of NTDs by periconceptional vitamin supplementation, N Engl J Med 1992
• NICE NG3 — Diabetes in pregnancy: management from preconception (recommendations)
• NICE evidence review — high-dose folic acid supplementation before and during pregnancy
• CDC/ATSDR — Recommendations to Improve Preconception Health and Health Care, MMWR 2006;55(RR-6)
• WHO Recommendations on Antenatal Care for a Positive Pregnancy Experience (2016)
• Sodium valproate in pregnancy and the Pregnancy Prevention Programme — BJGP
• First-trimester ACE-inhibitor / ARB exposure and adverse pregnancy outcomes — meta-analysis
• CDC — Guidelines for vaccinating pregnant women (live vaccines including MMR)
• Status of NTD prevention post folic-acid fortification in South Africa
• South Africa NDoH National Consolidated Guidelines (January 2026) — prevention of vertical transmission (PVT); preconception ART optimisation and viral suppression.
• South Africa NDoH Maternity Care Guidelines — opportunistic/every-contact preconception care within the public-sector model.