Voluntary pregnancy interruption, voluntary or elective abortion is the termination of pregnancy before fetal viability by request of the woman not for reasons of maternal health or fetal disease. Elective abortion is distinct from therapeutic or medical abortion, which is the termination of pregnancy before fetal viability to preserve the mother's health or due to fetal disease. Medical indications may include the following: when continuing with the pregnancy may threaten the life of the woman or seriously damage her health; when the pregnancy was the consequence of rape or incest; or when continuing with the pregnancy will lead to the birth of a child with severe physical malformations or mental retardation.1
The World Health Organization (WHO) defines unsafe abortion as “a procedure for terminating an unwanted pregnancy either by persons lacking the necessary skills or in an environment lacking minimal medical standards or both”2 (p.18) and which poses significant risks to the woman's health and life.2-5 This definition is linked to the process, but in another document, the WHO also specifies that the characteristics of an unsafe abortion have to do with inappropriate circumstances before, during and after abortion. The document further states the features commonly related to unsafe abortions: no pre-abortion counseling and advice; abortion is induced by an unskilled provider, frequently in unhygienic conditions or by a health practitioner outside official/adequate health facilities; abortion is self-induced by ingestion of traditional medication or hazardous substances and so on.5
The WHO estimates that of the 42 million pregnancies terminated worldwide each year due to induced abortions, 20 million are unsafe abortions, which lead to 80,000 maternal deaths and hundreds of thousands of disabilities. Clandestine abortions are the cause of one out of four of those deaths.2,6,7 In Africa, rates of unsafe abortions range between 18 and 39 per 1000 women of reproductive age; higher rates are found in the east of Africa and lower rates in the southern and northern territories of the continent.4 In Latin America and the Caribbean, estimated unsafe abortion rates range between 16 and 33 per 1000. In the Caribbean, the rate is lower because abortion is legal and accessible in Cuba. In Asia, with the exception of Japan, the unsafe abortion rate is 13 per 1000, 17 per 1000 in Oceania and three per 1000 in Europe.5,8
Regarding applicable laws, worldwide, legislation on abortion is very diverse. Forty per cent of people live in countries that forbid abortion completely or that allow it to be performed only to save the woman's life or protect her physical or mental health. In countries in which there is no legislation regarding elective abortion or which have restrictive abortion laws, high rates of clandestine unsafe abortions lacking any sort of essential interventions to prevent potential complications occur, which entail a severe risk for the women's health.4
Regarding interventions that should be performed to provide comprehensive abortion care, the WHO has published strategies used worldwide to reduce the number of deaths and complications caused by unsafe abortions and miscarriages. The care is built on five pillars, three of which we would like to highlight: (1) counseling to identify and meet women's emotional and physical health needs; (2) contraceptive and family planning services to help women prevent unwanted pregnancies; and (3) cooperation between the community and the service provider to prevent unwanted pregnancies and abortions at risk, and mobilize resources to help women to obtain proper and relevant care in case of abortion complications.2
One of the WHO's Millennium Health Goals for 2015 was to achieve a reduction in maternal mortality due to post-abortion complications by 75%, the main cause of such deaths being hemorrhaging or infections resulting from unsafe abortions (13%). Of the 20 million unsafe abortions taking place worldwide each year, 10–50% require medical assistance, thus legalizing this practice may contribute to the reduction of maternal mortality. In this regard, elective abortion care models are required to offer not only pre-abortion care but also post-abortion care, as well as safe procedures performed by professionals equipped with the adequate means.2,9-12
A review on the role of nursing in the management of unwanted pregnancies reveals that the assistance provided by the professionals (nurses and midwives) should focus primarily either on preconception counseling to couples looking for a wanted pregnancy or on contraception.13 This review with two Clinical Practice Guidelines features a series of recommendations regarding the interventions that should be performed throughout the process from a holistic perspective (i.e. before, during and after elective abortion).
The recommendations include strategies for the service organization (set up resources to provide information both to women and professionals, access guarantees to such resources without any restrictions based on age, ethnic origin, religious beliefs, disabilities, sexual orientation, marital status, number of previous abortions, etc.),13-16 pre-elective abortion interventions (performing an initial assessment, providing women with sufficient, adapted, objective and evidence-based information on complications, adverse effects and sequelae that may appear after abortion),14-17 interventions to prepare for the procedure (providing contact information with the abortion unit at the time of referral, offering the patient a choice in the technique used for elective abortion induction, providing local or general anesthesia in case of medical abortion, minimizing delays in the process, etc.),13-16 interventions when the woman has decided to undergo elective abortion (complementary tests to assess the risk of venous thromboembolisms and the presence of sexually transmitted diseases, cervical cytology, non-routine ultrasound scan and prevention of infectious complications) and making decisions together with the woman on which contraceptive methods are best suited for her and agreement on a contraceptive plan after the elective abortion.13-16
A systematic review with meta-analysis concluded that there was no evidence that supported contraceptive counseling at that point of the process increasing acceptance and use of contraceptive measures after an elective abortion.17 Interventions after the elective abortion is performed include performing a follow-up to exclude pregnancy continuation, presenting a record so that other services can follow up and manage potential complications, referrals for women who may require additional emotional support or whose mental health is considered to be at risk and providing information and counseling about the contraceptive method to be used and started immediately. Women who choose not to start immediately must be given information about local contraceptive providers (family doctor) and whenever necessary referred to the sexual healthcare service.13-15,18,19 Moreover, when treating a woman with an unwanted pregnancy who decides to have an elective abortion, there are two scenarios that require special attention: suspected abuse and possibility of mental illnesses.3,20-23
The Royal College of Obstetricians and Gynecologists (RCOG) also publishes recommendations about the interventions to be followed in said cases: draft guides about this additional help; written information about the risks and possible experiences that they may have after the procedure; identification of women who may require additional support and women with a psychiatric history, poor social support or lack of partner's support, proof of coercion and so on.21
Another controversial and contradicting complication is the relationship between elective abortion and mental problems. The most consistent predictor of mental disorders post-abortion is the presence of pre-existing mental disorders strongly associated with exposure to sexual abuse and domestic violence.22 A study confirmed the causal relationship between abortion and subsequent mental disorders even though said studies face methodological issues.24 Another study confirmed that the experience of abortion increases the risk of developing a wide range of psychopathological disorders: drug consumption, anxiety, hostility, low self-esteem, depression and bipolar disorder.25 A systematic review that evaluated potential psychological problems in the long-term for women in such circumstances revealed that a big part of the debate on this topic is based on the premise that women who undergo an elective abortion experience psychological anguish or “post-abortion syndrome”, which is similar to post-traumatic stress disorder. There were few differences between women who have abortions and their respective comparison groups in terms of mental health sequelae. Conversely, studies with a less-precise methodology did find negative mental health sequelae after abortion.26 In a cohort study, exposure to abortion represented 1.5–5.5% of the global rate of mental health disorders, and no consistent associations with mental health were found.27 Yet another study concluded that the risk of readmission in women with a psychiatric history was similar before and after a first abortion during the first trimester, in stark contrast with a marked increase of readmissions after delivery.28 In no way can any argument related to mental health be employed to induce abortion based on empirical foundations.28 Two reports from the RCOG and the American Psychological Association confirmed that there was no credible evidence that elective abortion performed in cases of unwanted pregnancy may be a threat to mental health. In cases in which a psychiatric disorder was identified, it was the result of a pre-existing psychological condition. The relative risk of mental health issues in women with unwanted pregnancies is higher than if they choose to have an elective abortion.21,29 A systematic review pointed out the importance of taking into account the need for support and attention all women with unwanted pregnancy require because the risk of developing mental health problems increases, regardless of the outcome of the pregnancy.30 However, irrespective of whether a relationship between elective abortion and mental health problems exists, this should not change the practice of providing mental health care to those women who have opted for elective abortion in the form of assessment and emotional support, referral if specialized care is required and so on.3,23 Moreover, there are two issues directly related to the professionals involved: conscientious objection and confidentiality. The legality of elective abortion requires that the healthcare personnel involved in the procedure (nurses, midwives, practitioners, etc.) are trained to provide the necessary care, and that the right to conscientious objection is respected. Professionals who resort to conscientious objection must inform women about their right to consult with other professionals who do not adhere to said objection, referring them promptly to such professionals.14,15,31-33
Some authors state that after a confirmed, unwanted pregnancy, the professional's religious or ethical ideologies must not prevail over the right of the woman to decide about her pregnancy.1 All women who request an elective abortion have the right to confidentiality. Only in exceptional circumstances, when the health, safety or wellbeing of a minor or other individuals are at risk, may the information be disclosed to third parties.34-36 In this review, we shall consider the relevance of facing the adverse consequences of unsafe abortion to the woman's health in order to develop recommendations for pre- and post-abortion care.6,37
There is a mutual influence among the physical, psychological and social aspects when an abortion occurs, given that the subject is a biopsychosocial being.38 The abortion itself will have an impact on the psychological aspects of the person due to trauma (responses in the form of sadness, irritability, euphoria, etc.) and also influence the interactions with social networks (social support) of women. The latter will influence positively or negatively on the women's health: integrating with or isolating from the nuclear family and/or social networks.
In view of the variability identified among the recommended interventions in terms of psychological and social aspects, this review aims to define and assess the efficacy of non-pharmacological interventions healthcare professionals provide and/or should provide to women before, during and after an elective abortion to reduce psychological and social morbidity. A preliminary search of the JBI Database of Systematic Reviews and Implementation Reports, the Cochrane Library, CINAHL, PubMed and PROSPERO revealed that there is not currently a systematic review (either published or underway) on this topic.
Types of participants
The current review will consider studies that include women (aged 13 years or more) who after an unwanted pregnancy decide to have an elective abortion.
Studies will be excluded from this review if they include women who have had a miscarriage or a therapeutic abortion.
Types of intervention(s)
The interventions included will be non-pharmacological interventions delivered by any health professional, designed to prevent and/or manage psychological and social morbidity related to an elective abortion and which are developed and delivered in both the hospital and community environments, such as: health education; emotional and psychological support; increase of support systems (family, social, health, etc.); family planning to prevent subsequent unwanted pregnancies, active listening, protection of the patients’ rights and risk identification (harmful substances, sexual abuse, violence, etc.); referral to the adequate services in case of substance abuse; environmental handling for prevention and protection from violence and/or abuse; training in relaxation and assertiveness techniques; enhancing self-esteem; promoting security, health and sexual education (safe sex, contraception, etc.) and management of self-injurious behavior. Studies on the use of pharmacological interventions will be excluded from the review.
We will attempt to classify and group those interventions found in the included studies according to the Nursing Interventions Classification as indicated in Appendix I.
Types of comparison: Studies that compare different non-pharmacological interventions among themselves or a non-pharmacological intervention versus no intervention will be included.
Any outcome variables that measure problems derived from elective abortion: empowerment and resilience; information processing skills (reproductive health, family planning etc.); family social adjustment; self-control of anxiety, fear and self-esteem; knowledge about and access to health resources; use of social support; elaboration of programs on sexual and reproductive health and care and follow-up; problem solving (family-related, cases of violence/abuse, consumption of harmful substances etc.); and quality of life, mood, substance-use control; and so on. All of these outcomes will be measured after the procedure.
The validated tools used to measure the outcomes of the included studies in the review may include the Rosenberg Self-Esteem Scale to measure self-esteem; the Hospital Anxiety and Depression Scale-Anxiety and Composite International Diagnostic Interview to assesses anxiety and depression; the Locus of Control from Rotter Scale to measure subjective wellbeing; the Impact of Event Scale to measure avoidance, grief/loss guilt/shame and quality of life;21 the Alcohol Use Disorders Identification Test to measure alcohol problems/illicit drug use;30 the Duke-UNK questionnaire that explores social support; the Indice de Ajuste Psicosocial to assess psychosocial adjustment; the Manheim Interview on Social Support to provide information on family support; the Family Apgar to explore the impact of family function on the health of its members;39 and so on.
We will attempt to classify and group those outcome variables found in the included studies according to the corresponding NOC, as indicated in Appendix I.
Types of studies
The current review will consider randomized controlled trials (RCTs), quasi-experimental non-randomized studies and observational studies (case-control and cohort studies).
The search strategy aims to find both published and unpublished studies. A three-step search strategy will be utilized in this review. An initial limited search of MEDLINE and CINAHL will be undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe articles. A second search using all identified keywords and index terms will then be undertaken across all included databases. Third, the reference list of all identified reports and articles will be searched for additional studies. The search strategy will include studies published in Spanish and English with no date restriction.
The search will be performed by means of the following keywords “natural language” (English and Spanish) and their corresponding MeSH terms, as shown below, categorized according to the type of participants, interventions and outcomes:
Participants: pregnant women, pregnancy in adolescence, unwanted pregnancy, abortion, induced abortion, elective abortion, pregnancy voluntary interruption, clandestine abortion and legal abortion.
Interventions: non-pharmacological interventions, care, social support, emotional support, family support, psychological Interview, health education, family planning, preventing pregnancy, contraceptive, sex education, patient safety, therapy, self concept therapy, counselling and postabortion.
Outcomes: empowerment, decision making, information processing, reproductive health, anxiety control, social adjustment, knowledge, self concept, patient satisfaction, physical morbidity, psychological distress, social isolation and resources uses.
Searches will be performed in the following databases:
MEDLINE (via PubMed)
CINAHL (including pre-CINAHL)
IME (Índice Médico Español, Spanish Medical Index) (database elaborated by the Centro Superior de Investigaciones Científicas – CSIC)
Cochrane Central Register of Controlled Trials – CENTRAL
PAHO (Pan American Health Organization)|http://www.paho.org/Spanish/dd/ikm/li/IMdatabase.htm).
Embase (Excerpta Medica data BASE)|http://www.embase.com/home
Search of unpublished or gray literature, post-graduate and doctoral theses and any unpublished studies to limit publication bias will be performed in the following sources:
WHO: World Health Organization|http://www.who.int/en/
Database for Spanish Dissertations and Theses (TESEO)
European Theses about Latin America|http://www.red-redial.net/bibliografia-documento-tesis.html
The DART-Europe E-theses Portal|http://www.dart-europe.eu/basic-search.php
Tesisdoctoralesen red (Doctoral theses in the web)|http://www.tdx.cat/
Open Thesis (worldwide theses)|http://www.openthesis.org/
ProQuest Dissertations and Theses Global|http://www.proquest.com/en-US/catalogs/databases/detail/pqdt.shtml
National Library of Medicine Gateway|http://gateway.nlm.nih.gov/gw/Cmd/
Grey Literature Report (via the New York Academy of Medicine website)|http://www.greylit.org/home
Grey Source (a selection of web-based resources in Grey Literature)|http://www.greynet.org/home.html
Searches will be performed in databases from professional and user associations:
FLASOG: Federación Latinoamericana de Sociedades de Obstetricia y Ginecología (Latin American Federation of Obstetrics and Gynecology)|www.flasgog.org
FIGO: International Federation of Gynecology and Obstetrics|www.figo.org
SEGO: Sociedad Española de Ginecología y Obstetricia (Spanish Society of Gynecology and Obstetrics)|www.sego.es
FAME: Federación de Asociaciones de Matronas de España (Federation of Midwives Associations of Spain)|www.federacion-matronas.org
EMA: European Midwives Association|http://www.europeanmidwives.org/
CIM: International Confederation of Midwives|http://www.internationalmidwives.org/
IPPF: International Planned Parenthood Federation|http://www.ippf.org ICMA: International Consortium for Medical Abortion|http://www.medicalabortionconsortium.org/
ACOG: American College of Obstetricians and Gynecologists|www.ACOG.org
IWHC: International Women's Health Coalition|http://www.iwhc.org
Ministerio de Sanidad, Servicios sociales e Igualdad. España. Observatorio de salud de la mujer (Ministry of Health, Social Services and Equality of Spain. Women's Health Observatory)|www.msssi.gob.es
The initial selection of articles will be carried out by two reviewers independently based on the title and the abstract. If in doubt or in the absence of an abstract, the full text of the document will be retrieved. Those reports for which the full text is retrieved and subsequently found not to meet the inclusion criteria will be rejected and listed with the reason for exclusion.
Assessment of methodological quality
Studies meeting the inclusion criteria will be assessed for methodological quality by two independent reviewers. For the purpose of critical appraisal, the Joanna Briggs Institute critical appraisal tools will be applied according to the type of study being appraised: RCTs and quasi-experimental studies (Appendix II) and cohort studies and case-control studies (Appendix III). Study selection will be done by consensus of the two reviewers. A study will be considered of acceptable quality for inclusion in the review whenever both reviewers rate as positive 70% or more of the items in their respective assessment tools. Any disagreements between reviewers will be resolved by discussion with a third reviewer.
Data from the studies included in the systematic review will be extracted independently by two reviewers using the standard tool for data extraction as set forth by the Joanna Briggs Institute (Appendix IV). Data extraction will consider features of the women, study design and study outcomes, interventions, sample size and so on. Any disagreements between reviewers will be resolved by discussion with a third reviewer. When needed, the reviewers shall contact the researchers to obtain additional information.
A narrative synthesis of the data will be performed. If the studies are comparable in terms of population, interventions, outcomes and study types, they will be analyzed via a meta-analysis using the Joanna Briggs Institute's SUMARI (System for the Unified Management, Assessment and Review of Information) software. Heterogeneity among studies will be estimated via the chi-square test, considering heterogeneity for values <0.05. The corresponding measures of the effect will be calculated by means of odds ratio (for dichotomous variable data) or weighted means differences (for continuous variables). For all analyses, 95% confidence intervals will be calculated. If meta-analysis is not possible, outcomes shall be presented in narrative form only.
Conflicts of interest
The reviewers are Spanish healthcare workers (from the Murcian Health Service, the Regional Ministry of Health and Social Policy of the Region of Murcia and the Health Services of Asturias) and they are not the authors of any of the studies included herein.
Appendix I: NANDA nursing diagnoses, NIC and NOC involved in voluntary interruption of unwanted pregnancy
Appendix II: MAStARI appraisal instrument for randomized controlled trials
Appendix III: MAStARI appraisal instrument for cohort studies and case-control studies
Appendix IV: MAStARI data extraction instrument
1. Pritchard JA, MacDonald P, Gant NW. Obstetricia. 3a ed.1993; México:Salvat, 4632.
2. World Health Organization, Department of Reproductive Health and ResearchSafe abortion: technical and policy guidance for health systems. 2nd ed.2012; Available from: http://www.who.int/es/
. [Accessed February 2015].
3. Rasch V. Unsafe abortion and postabortion care – an overview. Acta Obstet Gynecol Scand
2011; 90 7:692–700.
4. Billings DL, Benson J. Postabortion care in Latin America: policy and service recommendations from a decade of operations research. Health Policy Plan
2005; 20 3:158–166.
5. World Health OrganizationUnsafe abortion estimates. 6th ed.2008; Available from: www.who.int/en/
. [Accessed November 2013].
6. Hessini L. Global progress in abortion advocacy and policy: an assessment of the decade since ICPD. Reprod Health Matters
2005; 13 25:88–100.
7. Cook RJ, Dickens BM, Bliss LE. International developments in abortion law from 1988 to 1998. Am J Public Health
1999; 89 4:579–586.
8. Grimes DA, Bensen J, Singh S, Romero M, Ganatra B, Okonofua FE, et al Unsafe abortion: the preventable pandemic. 2006; Lancet:published online Nov 1. DOI: 10.1016/S0140-6736(06)69481-6.
9. RamaRao S, Townsend JW, Diop N, Raifman S. Postabortion care: going to scale. Int Perspect Sex Reprod Health
2011; 37 1:40–44.
10. Faúndes A, Rao K, Briozzo L. Right to protection from unsafe abortion and postabortion care. Int J Gynaecol Obstet
2009; 106 2:164–167. Epub 2009 Jun 18.
11. Renner RM, Brahmi D, Kapp N. Who can provide effective and safe termination of pregnancy care? A systematic review. BJOG
2013; 120 1:23–31.
12. Olukoya P. Reducing maternal mortality from unsafe abortion among adolescents in Africa. Afr J Reprod Health
2004; 8 1:57–62.
13. Levi AJ, Simmonds KE, Taylor D. The role of nursing in the management of unintended pregnancy. Nurs Clin North Am
2009; 44 3:301–314.
14. The Care of Women Requesting Induced Abortion Evidence-based Clinical Guideline Number 7. Royal College of Obstetricians and Gynaecologists. First published 2000. Revised edition published September 2004. This revised edition published November 2011.
15. Gogna MA, Binstock G, Fernández S, Ibarlucía I, Zamberlin N. Adolescent pregnancy in Argentina: evidence-based recommendations for public policies. Reprod Health Matters
2008; 16 31:192–201.
16. Vlemmix F, Warendorf JK, Rosman AN, Kok M, Mol BW, Morris JM, et al Decision aids to improve informed decision-making in pregnancy care: a systematic review. BJOG
2013; 120 3:257–266.
17. Ferreira AL, Lemos A, Figueiroa JN, de Souza AI. Effectiveness of contraceptive counselling of women following an abortion: a systematic review and meta-analysis. Eur J Contracept Reprod Health Care
2009; 14 1:1–9.
18. Grossman D, Ellertson C, Grimes DA, Walker D. Routine follow-up visits after first-trimester induced abortion. Obstet Gynecol
2004; 103 4:738–745.
19. Adinma JI, Ikeako L, Adinma ED, Ezeama CO, Ugboaja JO. Awareness and practice of post abortion care services among health care professionals in southeastern Nigeria. Southeast Asian J Trop Med Public Health
2010; 41 3:696–704.
20. Foy R, Penney GC, Grimshaw JM, Ramsay CR, Walker AE, MacLennan G, et al A randomised controlled trial of a tailored multifaceted strategy to promote implementation of a clinical guideline on induced abortion care. BJOG
2004; 111 7:726–733.
21. Royal College of Obstetricians and GynaecologistAbortion and mental health – the O&G perspective. August 2008; Available from: www.rcog.org
. [Accessed November 2013].
22. Robinson GE, Stotland NL, Russo NF, Lang JA, Occhiogrosso M. Is there an “abortion trauma syndrome”? Critiquing the evidence. Harv Rev Psychiatry
2009; 17 4:268–290.
23. Munk-Olsen T, Laursen TM, Pedersen CB, Lidegaard O, Mortensen PB. First-time first-trimester induced abortion and risk of readmission to a psychiatric hospital in women with a history of treated mental disorder. Arch Gen Psychiatry
2012; 69 2:159–165.
24. Major B, Appelbaum M, Beckman L, Dutton MA, Russo NF, West C. Abortion and mental health: evaluating the evidence. Am Psychol
2009; 64 9:863–890.
25. Lorente PA. Psychopathology and abortion. Cuad Bioet
2009; 20 70:357–380.
26. Charles VE, Polis CB, Sridhara SK, Blum RW. Abortion and long-term mental health outcomes: a systematic review of the evidence. Contraception
2008; 78 6:436–450.
27. Fergusson DM, Horwood LJ, Boden JM. Abortion and mental health disorders: evidence from a 30-year longitudinal study. Br J Psychiatry
2008; 193 6:444–451.
28. Gurpegui M, Jurado D. Psychiatric complications of abortion. Cuad Bioet
2009; 20 70:381–392.
29. American Psychological Association, Task Force on Mental Health and AbortionReport of the Task Force on Mental Health and Abortion. 2008; Washington, DC:APA, Available from: www.apa.org/
. [Accessed November 2013].
30. National Collaborating Centre for Mental HealthInduced abortion and mental health. A systematic review of the mental health outcomes of induced abortion, including their prevalence and associated factors. London:Academy of Medical Royal Colleges; 2011.
31. General Medical CouncilPersonal beliefs and medical practice – guidance for doctors. 2008; London:GMC, Available from: www.gmc-uk.org/
. [Accessed November 2013].
32. Royal College of NursingAbortion care: RCN guidance for nurses, midwives and specialist community public health nurses. 2008; London:RCN, Available from: http://www.rcn.org.uk/
. [Accessed November 2013].
33. Nursing and Midwifery CouncilConscientious objection. Advice sheet. 2008; Available from: http://www.nmcuk.org/
. [Accessed November 2013].
34. Department of HealthConfidentiality: NHS Code of Practice. 2003; London:Department of Health, Available from: www.dh.gov.uk/
. [Accessed November 2013].
35. Department for Children, Schools and FamiliesInformation sharing: guidance for practitioners and managers. 2008; Nottingham:Department for Children, Schools and Families, and Communities and Local Government, Available from: www.teachernet.gov.uk/
. [Accessed November 2013].
36. The Scottish GovernmentNHS Scotland Code of Practice on Protecting Patient Confidentiality. 2010; Edinburgh:The Scottish Government, Available from: www.knowledge.scot.nhs.uk/
. [Accessed November 2013].
37. Murty J. When a patient requests an abortion. Practitioner
2000; 244 1608:204–206. 208, 210-1.
38. Izzedin Bouquet de Durán R. Aborto espontáneo. Liberabit Lima
2012; 18 1:53–58.
39. Badía X. La medida de la salud. Guía de escalas de medición en español. 4a ed.Madrid:Unión Editorial; 2007.