ti®c community and provide key data relative to folate utilizationand requirements during the third trimester.

However, the authors have incorrectly indicated that there is adiscrepancy with data published by our research group regardingthe observation that folate excretion was not higher in the secondtrimester (14-25 weeks gestation) compared to nonpregnantcontrols2. A major difference between the two studies is the de®ni-tion of the trimesters. In the United States the ®rst trimester is until13 or 14 weeks gestation, the second trimester from 14 or 15-28weeks, and the third trimester from 28 or 29-42 weeks3,4. In thestudy by Higgins folate catabolism was measured at 12-16 weeksgestation, 26-30 weeks and 34 1 weeks gestation, but the resultsare present as `trimesters' (Table 3). The time period during preg-nancy selected to represent the second trimester (26-30) weeksscarcely overlaps with the second trimester in our study or withestablished criteria3,4. Higgins et al.1 state that their data indicatethat the increase in folate catabolites was found only in the thirdtrimester. Our study was limited to a comparison of folate catabo-lites during the second trimester relative to nonpregnant controlsand did not include pregnant women in the third trimester.

A second problem is their statement that an analytical error in ourpart resulted in an incomplete and inaccurate quantitation of urinarycatabolites. The percentage recovery was applied in the samemanner to samples from both pregnant and nonpregnant women;therefore `lower concentrations' in pregnant women could not haveresulted due to the proposed analytical error. Our research groupcommunicated with the authors and suggested that they analyse oursamples to rule out analytical differences between the laboratories.Two shipments of urine samples were sent from our laboratory toIreland and were analysed by two of the authors. The samples werecoded such that the pregnancy status and total urine volume was notidenti®ed. Their analysis of our samples con®rmed that there wereno differences between folate catabolites excreted by pregnantwomen in the second trimester and nonpregnant women.

The data presented by Higgins et al. show that the signi®cantincrease in folate catabolites occurs after 34 weeks gestation andnot during the 14-28 weeks gestation study. This fact is enor-mously important since this is the period of gestation that coincideswith an increase in fetal size and in which maternal folate de®-ciency has most often been documented.

References

1. Higgins JR, Quinlivan EP, McPartlin J, Scott JM, Weir DG, Darling

MRN. The relationship between increased folate catabolism and the

increased requirement for folate in pregnancy. Br J Obstet Gynaecol

2000;107:1149±1154.

2. Caudill MA, Gregory JF, Hutson AD, Bailey LB. Folate catabolism in

pregnant and nonpregnant women with controlled folate intake. J Nutr

1998;128:204±208.

3. Cunningham, et al. Prenatal care. In: Williams Obstetrics. Appleton &

Lange: Stamford, Connecticut, 1997:229.

4. American College of Obstetricians and Gynecologists, Washington DC.

In: Encyclopedia of Women's Health and Wellness, 2000.

Lynn B. Baileya, Jesse F. Gregorya, Marie Caudilla &Amelia Cruzb

aDepartment of Food Science and Human Nutrition, University ofFlorida, USAbDepartment of Obstetrics and Gynecology, University of Florida,USA

PII: S0306-5456(00)00162-5

The management of menorrhagia ± SMART study(Satisfaction with Mirena and Ablation: a RandomisedTrial)

Sir,We read with disappointment the letter by Rogerson et al. that

the SMART Study was closed owing to a poor recruitment rate1.On a brighter note, we wish to make readers aware of a similarrandomised trial known as TALIS (Thermo-Ablation versus theLevonorgestrel Intrauterine System). The TALIS Trial is asingle-centre, randomised, controlled trial of the Thermachoiceballoon endometrial ablation system (Johnson & Johnson Medical,New Zealand) versus the levonorgestrel intrauterine system(Mirena, Schering) for heavy menstrual bleeding. The trial isbeing conducted by the University Department of Obstetrics andGynaecology at the National Women's Hospital, Auckland, NewZealand and has been recruiting since April 1999.

The primary objective, similar to the SMART study, is to ascer-tain whether the levonorgestrel intrauterine system is equivalent toendometrial ablation performed by the most widely evaluatedsecond generation technique (heated ¯uid balloon ablation usingthe Thermachoice system) in terms of the women's satisfaction andan assessment of heaviness of menstrual bleeding by the pictorialblood-loss assessment chart, at a 12-month post-treatment assess-ment. The treatments, preceded by a hysterectomy, performed inthe out-patient clinic using paracervical local anaesthesia and intra-venous analgesia if required. Secondary outcome measures ofdiscontinuation rates, various quality of life measures and cost oftreatment will also be assessed. Follow up for the TALIS Trialinvolves assessments at three, six and twelve months, thenannually up to ®ve years.

We believe from our calculation that 80 women would berequired for the trial and will give suf®cient power to answer thequestion asked, although comments from respected sources havesuggested that this is an underestimate of the number required1,2.Given the recruitment dif®culties experienced in the SMARTstudy, the alternative approach is to perform a meta-analysis ofrandomised trials assessing the same interventions. This approachhas been used successfully by the Cochrane Menstrual Disordersand Subfertility Group to assess the impact of various interventionsfor menstrual disorders3 - a strength of the Cochrane systematicreviews is that they are updated as more data become available.Thus, the SMART study could still generate data which would beof use in such a meta-analysis.

Recruitment for the TALIS Trial has been more successful. 101women have been seen in our Menstrual Disorders Research Clinicover an 18-month period. 20 women were ineligible (the majorityowing to previously undiagnosed uterine abnormalities (predomi-nantly ®broids) or non-cyclical dysfunctional uterine bleeding). Ofthe 81 women who were offered entry to the trial, 62 have beenrandomised and treated, three await randomisation, and only 16declined the trial. Of those who declined, only three were unwillingto accept randomisation; seven felt their menorrhagia resolvedafter the ®rst visit, four insisted on a hysterectomy and two wishedto try tranexamic acid ®rst. The almost universal refusal to acceptrandomisation to Mirena amongst those declining the SMARTstudy1 has not been an issue at all in Auckland.

Why has the TALIS Trial recruitment been successful? Anumber of explanations are possible: women in New Zealandmay be more receptive to research; public opinion of intrauterinedevices may be more favourable than in the United Kingdom; theTALIS study design may allow more time for decisions to bemade. The time for a `®rst consultation' in our research clinic is60 to 90 minutes, although this does include a transvaginal ultra-sound scan and pelvic examination with endometrial sampling.Women are made aware that the two treatments available in the

CORRESPONDENCE 773

trial are effective in their own right. A further incentive for invol-vement in the trial is the concept of the `one-stop' (or `two-stop' inthe case of our research clinic) menstrual disorders clinic. This typeof clinic had not previously been established in our hospital andwomen otherwise have their menorrhagia managed routinely in ageneral gynaecology clinic. On completion of the trial, the dedi-cated menstrual disorders clinic will continue as a routine clinicalservice.

To answer the question asked by the SMART study trialists -ªshould we disregard evidence based medicine and prescribe suchtherapies without proof?º No, but we may need to be patient in thearrival at such proof, which could involve meta-analysis of rando-mised trials as SMART and TALIS.

References

1. Rogerson L, Duffy S, Crocombe W, Stead M, Dawood D. Management

of menorrhagia - SMART study (Satisfaction with Mirena and Ablation:

a Randomised Trail)[Correspondence]. Br J Obstet Gynaecol

2000;107:1325±1326.

2. Cooper KG, Parkin DE, Garratt AM, Grant AM. Two-year follow up of

women randomised to medical management or transervical resection of

the endometrium for heavy menstrual loss: clinical and quality of life

outcomes. Br J Obstet Gynaecol 1999;106:1231±1232.

3. Lethaby AE, Cooke I, Rees M. Progesterone/progestogen releasing

intrauterine systems versus either placebo or any other medication for

heavy menstrual bleeding (Cochrane Review). In: The Cochrane

Library, Issue 4. Oxford: Update Software, 2000.

Neil Johnson, Richard Bus®eld, Lynn Sadler, Anne Lethaby &Cindy FarquharDepartment of Obstetrics and Gynaecology, National Women'sHospital, University of Auckland, New Zealand

PII: S0306-5456(00)00163-7

Postpartum depression: identi®cation of women at risk

Sir,We read with interest the article by Forman et al.1, and would

like to congratulate them on their enormous effort in conductingthis study of such a large cohort. However, our interpretation of theresults of the study is somewhat at variance with the opinions of theinvestigators.

First, it should be pointed out that the low prevalence of post-partum depression found in this study was low point prevalenceand not period prevalence. Using the same instrument (i.e. theEdinburgh Postnatal Depression Scale), Cox et al.2 have shownthat while the point prevalence of depression at 6 months postpar-tum was 9.1%, the six-month period prevalence was 13.8%. Thus alow point prevalence rate does not equate to low prevalence ofpostpartum depression in a certain population.

Second, the literature suggested that the rates of depression aresimilar between pregnancy and the postpartum period3, and nodifference in either the six-month prevalence or period prevalencecould be demonstrated between postnatal and non-pregnant controlwomen2. In addition, the onset of depression was threefold higherin the ®rst ®ve weeks postpartum2 and lasting up to three months4,and the risk factors identi®ed indicated that the depressed womenwere those with either pre-existing depression or with a dispositiontowards depression that was unmasked by pregnancy. Takentogether with the aforementioned reports, we suspect that what

was found in this study was not the prevalence of postpartumdepression, but rather the prevalence of depression in womenwho happened to have a predilection to depression, and whichmight have been unmasked by childbirth, four months before theadministration of the Edinburgh Postnatal Depression Scale. Wealso suspect that the point prevalence found in this study would beno different from that in non-pregnant women in the same region.Could the investigators explain the reason for performing thescreening at four months postpartum, and inform us of the inci-dence of the various forms of depression in the non-pregnant oroverall population in their country?

References

1. Nielsen Form D, Videbech P, Hedegaard M, Dalby Salvig J, Secher NJ.

Postpartum depression: identi®cation of women at risk. Br J Obstet

Gynaecol 2000;107:1210±1217.

2. Cox JL, Murray D, Chapman G. A controlled study of the onset, dura-

tion and prevalence of postnatal depression. Br J Psychiatry

1993;163:27±31.

3. O'Hara MW, Zekoski EM, Phillips LH, Wright EJ. Controlled prospec-

tive study of postpartum mood disorders: comparison of childbearing

and nonchildbearing women. J Abnorm Psychol 1990;99:3±15.

4. Cox JL, Rooney A, Thomas PF. How accurately do mothers recall

postnatal depression? Further data from a 3-year follow-up study. J

Psychosom Obstet Gynecol 1984;3:185±187.

Lai Fong Ho & Terence LaoDepartment of Obstetrics and Gynaecology, and the University ofHong Kong, Tsan Yuk Hospital, Hong Kong

PII: S0306-5456(00)00164-9

Authorsuthors' Replyeply

Sir,We would like to thank Lai Fong Ho and Terence Lao for their

interesting remarks on our article. They are concerned about pointprevalence and period prevalence when comparing postpartumdepression in different populations. We have clearly de®ned theprevalence estimate as a point prevalence in our paper. Likewisethe prevalence estimates to which we refer in the literature are aspoint prevalences.

Ho and Lao ask about the reason for performing screening atfour months postpartum. This was based on a pilot study in womenreceiving a similar from of antenatal care. 271 women werecontacted by mail 9 months postpartum asking about depressivesymptoms. In this pilot study depressive symptoms showed a peakat 4 months postpartum.

Ho and Lao ask for estimates of the prevalence of depression inour nonpregnant population. No studies information is available.As we point out in our article our data do not support the hypothesisthat pregnancy or delivery per se should cause postpartum depres-sion; neither can we conclude that depressive symptoms were notpresent antenatally. We do suggest that postpartum depression is acontinuum of depressive symptoms deteriorating over time; thisview is supported by the fact that psychological distress was thestrongest antenatal predictor of postpartum depression. We agreewith Ho and Lao that depression could have been present antena-tally and may have been unmasked by childbirth. Our study hasidenti®ed important factors in antenatal care which may help in the

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