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National Collaborating Centre for Women's and Children's Health (UK). Hypertension in Pregnancy: The Management of Hypertensive Disorders During Pregnancy. London: RCOG Press; 2010 Aug. (NICE Clinical Guidelines, No. 107.)

11Breastfeeding

11.1. Introduction

Breastfeeding is the feeding method of choice and encouraging breastfeeding is a key priority for maternity care providers (whether working in hospital or in primary care; see ‘Postnatal care’, NICE clinical guideline 37).29 While hypertension is not in itself a contraindication to breastfeeding, the compatibility of antihypertensive drugs with breastfeeding may be an issue for discussion between women with hypertensive disorders and their healthcare providers. In this section, the GDG sought to identify evidence in relation to the safety of antihypertensive agents during breastfeeding.

11.2. Antihypertensive agents and breastfeeding

Clinical effectiveness

No clinical studies were identified in relation to the compatibility of antihypertensive drugs and breastfeeding (that is, in terms of adverse effects on babies whose mothers were taking antihypertensive agents while breastfeeding). However, a number of studies reported non-clinical outcomes (such as excretion of particular drugs in breast milk or detection in maternal or infant blood plasma). These studies are summarised in Table 11.1. Further details (including data for other antihypertensive drugs) are provided in Appendices M and N.

Table 11.1. Summary of studies evaluating the safety of antihypertensives commonly used during breastfeeding.

Table 11.1

Summary of studies evaluating the safety of antihypertensives commonly used during breastfeeding.

Evidence statement

No clinical studies were identified in relation to the compatibility of antihypertensive drugs and breastfeeding. A number of studies reported that the following drugs were excreted in breast milk of women who were taking antihypertensives or were detected in maternal or infant blood plasma:

GDG interpretation of the evidence

The GDG is aware of an MHRA newsletter (May 2009 issue of the MHRA Drug Safety Update, available at www.mhra.gov.uk/Publications/Safetyguidance/DrugSafetyUpdate/CON046451) that identifies methyldopa as the antihypertensive of choice during breastfeeding. However, the MHRA Drug Safety Update does not reflect the association between methyldopa and clinical depression, and the GDG’s view is that methyldopa should not be used in the postnatal period because women are already at risk of depression at this time (see Section 4.8). The MHRA Drug Safety Update notes that ‘ACE inhibitors have a small molecular size and so their transfer to breast milk is possible. Data on the use of ACE inhibitors in breastfeeding are sparse and relate mostly to captopril, enalapril, and quinapril; findings indicate that drug is transferred to breast milk. Although the levels transferred to an infant via breastfeeding are unlikely to be clinically relevant, there are insufficient data to exclude a possible risk of profound neonatal hypotension, particularly in preterm babies.’ The MHRA Drug Safety Update draws on exactly the same studies considered by the GDG in relation to enalapril and captopril (see Table 11.1) but reaches a different interpretation of the evidence. Neither of the studies considered in relation to enalapril and captopril provided data on infant outcomes (such as blood plasma concentrations of the drugs following breastfeeding, or adverse clinical outcomes). The evidence considered by the MHRA in relation to quinapril is not relevant to the current discussion as the GDG did not wish to recommend its use during breastfeeding.

The GDG noted that there is very little good evidence on the compatibility of antihypertensive drugs and breastfeeding, particularly for clinical outcomes, and that most of the commonly used antihypertensive drugs appear to be safe for the baby (including labetalol, nifedipine and methyldopa, which are the drugs most likely to be used by women with gestational hypertension). The consensus view of the GDG was that the benefits to the mother and the baby of breastfeeding (and/or the baby receiving the mother’s expressed breast milk) far outweigh potential risks to the baby of transfer of antihypertensive drugs in breast milk. The GDG noted that if ACE inhibitors were needed during the postnatal period then enalapril and captopril were the recommended drugs in this class (because of the quality and quantity of associated safety data), even though they are not used widely outside pregnancy.

The GDG also reflected on the risk of neonatal hypoglycaemia or poor establishment of feeding in babies born to women with hypertensive disorders during pregnancy (owing to the increased risk of being born preterm (including some who would be born at 34–36 weeks), SGA or exposed to antihypertensive drugs antenatally). Such babies will require a period of clinical monitoring (possibly including blood glucose monitoring) and assessment of adequacy of feeding). In these circumstances, the woman should be advised that she and the baby are likely to need to stay in hospital for at least 48 hours after the birth to ensure adequacy of feeding and prevention of hypoglycaemia before discharge. Thus guidance about how long a mother needs to stay in hospital should take into account both the mother’s and baby’s wellbeing. Detailed recommendations for postnatal care of the baby are outside the scope of this guideline, but the GDG’s view is that the baby’s wellbeing and adequacy of feeding should be assessed at least daily for the first 2 days after the birth. The GDG’s recommendations in relation to the drugs to use during breastfeeding are consistent with the recommended framework for monitoring of the baby. The GDG also highlighted the potential benefits of offering parents information and advice to enable them to assess their baby’s general condition and to identify signs and symptoms of common health problems seen in babies and how to contact a healthcare professional or emergency service if required (see ‘Postnatal care’, NICE clinical guideline 37).29

Recommendations

In women who still need antihypertensive treatment in the postnatal period, avoid diuretic treatment for hypertension if the woman is breastfeeding or expressing milk.

Tell women who still need antihypertensive treatment in the postnatal period that the following antihypertensive drugs have no known adverse effects on babies receiving breast milk:

Tell women who still need antihypertensive treatment in the postnatal period that there is insufficient evidence on the safety in babies receiving breast milk of the following antihypertensive drugs:

Assess the clinical wellbeing of the baby, especially adequacy of feeding, at least daily for the first 2 days after the birth.

This guideline assumes that prescribers will use a drug’s summary of product characteristics (SPC) to inform decisions made with individual patients. Drugs for which particular attention should be paid to the contraindications and special warnings during pregnancy and lactation are marked with † and detailed in Section 1.6.

Research recommendation

How safe are commonly used antihypertensive agents when used by women who are breastfeeding?

Why this is important

With the increasing incidence of hypertensive disorders during pregnancy, more pregnant and breastfeeding women will potentially be exposed to antihypertensive medication. Most of the relevant drugs are not licensed for use in pregnancy. For most drugs there is no information on their presence in human breast milk, or if such a presence has any clinical effect. As a result, women may either be denied effective treatment in the postnatal period or advised against breastfeeding. Studies should measure the concentration of relevant drugs and their metabolites in breast milk, taking account of drug pharmacokinetics (peak levels and elimination) and comparing neonatal behaviour and physiological variables in women using each drug with those in women who choose not to breastfeed. Studies should follow women and their babies for long enough to exclude cumulative effects and they should be large enough to provide reassurance to licensing and drug regulating authorities.

Copyright © 2011, Royal College of Obstetricians and Gynaecologists.

No part of this publication may be reproduced, stored or transmitted in any form or by any means, without the prior written permission of the publisher or, in the case of reprographic reproduction, in accordance with the terms of licences issued by the Copyright Licensing Agency in the UK [www.cla.co.uk]. Enquiries concerning reproduction outside the terms stated here should be sent to the publisher at the UK address printed on this page.

The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore for general use.

Cover of Hypertension in Pregnancy
Hypertension in Pregnancy: The Management of Hypertensive Disorders During Pregnancy.
NICE Clinical Guidelines, No. 107.
National Collaborating Centre for Women's and Children's Health (UK).
London: RCOG Press; 2010 Aug.

NICE (National Institute for Health and Care Excellence)

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