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PAPERS: Agustin Conde-Agudelo and José M Belizán Maternal morbidity and mortality associated with interpregnancy interval: cross sectional study BMJ 2000; 321: 1255-1259 [Abstract] [Full text]

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Other Important Considerations in Interpregnancy Interval

Eithne Linnane   (24 November 2000)

Re: Other Important Considerations in Interpregnancy Interval

Agustin Conde-Agudelo, José M Belizán   (14 December 2000)

Other Important Considerations in Interpregnancy Interval 24 November 2000
Eithne Linnane, Specialist Registrar in Public Health Medicine Bro Taf Health Authority, Temple of Peace Health, Cathays Park, Cardiff, CF13NW Send response to journal: Re: Other Important Considerations in Interpregnancy Interval	Editor--Conde-Agudelo et al1 have examined the effect of pregnancy interval on maternal morbidity and mortality. Specifically they looked at 456,889 births over a twelve-year period as recorded in a database that registers half a million births a year. We welcome their study; however, their methodology raises some concerns. Firstly, the study is not population based but rather hospital based and therefore represents less than 2% of all births in the Latin American and Caribbean region. As a result, they have probably excluded all isolated or community births which tend to occur more frequently among vulnerable mothers anyway. Therefore, how representative is their sample of the whole population? This would threaten the generaliseability of their findings both to the developed world and to the rest of Latin American and the Caribbean. Secondly there is no detail about the CAVEAT’s that should be applied to data from databases and surveillance systems. (C = completeness, A = accurate, V = valid, E = evaluated, A = available, T = timely.) Thirdly, the authors appear not to have considered socio-economic factors other than maternal education and cohabitation of parents, which by themselves may not be the most appropriate markers. Given the vastly disparate cultural areas they covered, should a variable relating to ethnic origin or religious persuasion also be included to be more meaningful here and for use in other studies? The authors explained an increased risk of eclampsia and pre-eclampsia amongst women with an interpregnancy interval of five years or more by suggesting that a protective effect from an earlier pregnancy wanes after five years. However, more conventional theories of the pathogenesis of pre -eclampsia suggest that maternal exposure to a paternal antigen is responsible.2 3 These more conventional hypotheses suggests that second pregnancies are less likely to result in pre-eclampsia if the first one was event free. This paper does not contradict this hypothesis, since long interpregnancy intervals may actually be associated with the acquisition of new reproductive partners. The findings on long interpregnancy interval would be of much greater interest had partner data been included. Finally, the authors concluded by recommending family planning to increase interpregnancy intervals and thus avoid the risks of short intervals. While this is a valid suggestion the opportunity to compare short interpregnancy interval risks with those of contraceptive is needed. Competing interests:None declared. Eithne Linnane, Specialist Registrar in Public Health Medicine, Philip Watson, Specialist Registrar in Public Health Medicine, Bro Taf Health Authority, Temple of Peace and Health, Cathays Park, Cardiff, CF13NW 1 Conde-Agudelo A, Belizán JM. Maternal morbidity and mortality associated with interpregnancy interval :cross sectional study. BMJ 2000;321:1255-1259.(18 November.) 2 Trupin LS,Simon LP,Eskenazi B. Change in paternity:a risk factor for preeclampsia in multiparas. Epidemiology1996;7:240-4. 3 Dekker GA, Robillard PY, Hulsey TC. Immune maladaptation in the etiology of preeclampsia: a review of corroborative epidemiologic studies. Obstetrical and Gynaecological survey. 1998;53(6):377-82.
Re: Other Important Considerations in Interpregnancy Interval 14 December 2000
Agustin Conde-Agudelo Fundación Clinica Valle del Lili, José M Belizán Send response to journal: Re: Re: Other Important Considerations in Interpregnancy Interval	We are gratified by the interest in our study expressed by Linnane et al. It is worthwhile to mention that all their concerns regarding the methodology of our research were discussed by us in the paper. Firstly, since less than 2% of all Latin American births are represented by our database, our results may not be generalised to the whole of the Latin American population and to the developed world. However, when we replicated the entire analyses by country, the effects of interpregnancy interval on maternal morbidity were essentially unchanged. The few maternal deaths did not allow us to analyse by country. Secondly, of the 520 689 parous women recorded in our database, we excluded 63 800 (12.3%) for whom information on interpregnancy interval or adverse maternal outcomes was missing or implausible. As stated in our paper, the accuracy of specific diagnoses registered in our database has not been extensively checked and only local medical record verifications were done. Therefore, our data are limited to a certain extent. However, overall rates of adverse maternal outcomes in this data set were similar to those reported in other studies, which would add support to the accuracy of diagnoses. Thirdly, in the present study we were unable to evaluate socio-economic factors other than maternal education and cohabitation of parents because these data were not available from the database. We agree that future studies could consider other socio-economic factors such as family income and race. However, it is not easy to include a variable relating to ethnic origin due to the great mixture of races in Latin America and the Caribbean. With regard to religious persuasion, it is doubtful that this variable is related to socio-economic condition in Latin America and the Caribbean. Fourthly, we agree that the relation between long interpregnancy interval and preeclampsia-eclampsia could be confounded by change of partner. However, we have controlled for the influence of other possible confounding factors of this relation, such as older age, history of chronic hypertension, and elevated body mass index before pregnancy, and lack of previous miscarriage and smoking. The variable change in paternity was not available to us for analysis. Thanks again for their interest in our work. Agustín Conde-Agudelo and José M. Belizán