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EARLY PREGNANCY: Biology and Medicine Editor-in-Chief: Eytan R. Barnea MD, FACOG

July 2001
Volume V, Number 3
ISSN: 1537-6583
Pages: 201-210

Multifetal Pregnancy Reduction and Halakha

Ilana Chertok
Neot Hadar 96, Yeroham, Israel, 011-972-8-6583319

Key Words: Halakha, multifetal reduction, selective termination

Acknowledgements: The author wishes to thank Dr. Zeev Silverman for his helpful critique and comments and Professor Shimon Glick and Dr. Neil Wenger for their guidance and direction

Abstract

The frequency of multifetal pregnancies has increased dramatically in recent years with the advent of assisted reproductive technologies. In an effort to ensure a successful outcome for both the fetus(es) and the mother, multifetal reduction is often medically recommended. Multifetal reduction may present a challenge to Orthodox Jewish law, as there is an apparent threat to the preservation of the fetuses’ lives. Yet, without medical intervention there is an increased risk of fetal and maternal morbidity and mortality. The issues involved in multifetal reduction have been thoroughly analyzed and recorded in Orthodox Jewish responsa, setting guidelines for rabbinic authorities to rule on the matter in specific cases based on the specific circumstances. The present article will analyze the medical procedure with respect to the halakhic literature published to date on the subject of multifetal reduction.

Introduction

Recent advances in medical technology have succeeded in enabling couples who were previously considered infertile to conceive and to bear children. Through fertility drug treatment, the risk of multifetal pregnancy increases as a result of ovarian stimulation causing an increased production of ova. The procedure of in vitro fertilization often results in multifetal pregnancy due to multiple implantation in an effort to increase the chance of successful outcome. In their article titled, "An Ethical Approach to Assisted Reproduction," Drs. Wenger and DeCherney describe the epidemiological increase in multiple births in the United States in recent years. Prior to the popularization of fertility treatments, the frequency of twin births was one in every ninety births. By 1997, the frequency increased to one in 37 births.¹ While the advances in assisted reproductive technologies are benefiting many couples who would otherwise be unable to bear children, the outcomes of fertility treatments may pose maternal and fetal risks. With the increasing number of fetuses, there is an increase in the risks of fetal anomalies, premature delivery, and spontaneous abortion.

In response to this predicament, multifetal reduction is aimed at reducing the risks associated with multifetal pregnancy. In addition to the medical, technical, and financial dilemmas posed by multifetal reduction, ethical dilemmas also arise such as whether to abort and if so, how and when to abort and which fetuses. Regarding childbearing as a primary value in Judaism, Halakha usually permits the use of assisted reproductive technologies, and must therefore address the issues associated with such treatments. This paper will concentrate on the ethical issues involved in multifetal reduction from a halakhic, or Orthodox Jewish perspective.

Risks of Multifetal Pregnancy
Fertility treatments causing ovarian stimulation often result in multiple, typically heterozygous fetuses. Likewise, in vitro fertilization is associated with multiple pregnancy because of the insertion of multiple fertilized eggs to increase the chance of successful implantation. Since each fetus carries its own probability of being affected by a chromosomal anomaly, the overall risk of Mendelian and chromosomal abnormality increases with the number of fetuses.² With monozygotic twins, for example, the rate of chromosomal anomalies is similar to that of singletons, but the risk of structural malformations increases.³ Thus, in twins, the risk of fetal anomaly in at least one fetus is more than twice that of singletons.⁴ Premature delivery is another risk associated with multiple pregnancy that increases the risk of infant morbidity and mortality, as is spontaneous abortion (both early and late) and fetal growth retardation.⁵ Potential maternal complications associated with multiple pregnancy are increased risk of pregnancy-induced hypertension, preeclampsia, polyhydramnios and severe anemia, as well as those general risks associated with long hospitalizations.⁶ Psychosocial disturbances to the mother are associated with the abovementioned risk factors that increase with multiple pregnancy, especially in light of the fact that many of the women who experience multiple pregnancy have undergone prolonged and emotionally distressing treatment for infertility.

Reduction Technique
Two types of multifetal reduction will be discussed, selective termination and multifetal reduction (non-selective). By definition, "selective termination" is the procedure of fetal reduction undertaken following the diagnosis of some abnormality. "Multifetal reduction" is the procedure whereby fetal abortion is performed with the intention of reducing the number of fetuses independent of fetal anomalies.⁷

Multifetal reduction is usually performed by one of two methods during the first trimester. A significantly higher risk of pregnancy loss is associated with fetal reduction after the first trimester.⁸ The most common method of reduction is the transabdominal injection of potassium chloride into the fetal cardiac region, usually performed at or after the ninth week of gestation. The overall rate of total pregnancy loss resulting from the attempt at reduction prior to 24 weeks gestation is 11.7%.⁹ The risk of total pregnancy loss with the reduction procedure increases with the number of fetuses such that the reduction of an initial triplet pregnancy carries a 7.6% loss rate increasing to 15.3% with higher multifetal pregnancies.¹⁰ The second method is transvaginal embryo aspiration using an ultrasound with a transvaginal transducer and puncture guide, through which a syringe may be inserted to suction out the embryo(s). This procedure may be performed earlier in gestation than the injection of potassium chloride, from approximately seven weeks gestation. Researchers found this method to have a significantly lower rate of total pregnancy loss, with an overall loss rate of 6.7% prior to 24 weeks gestation. In a subset of 39 women with higher order gestational pregnancies (>4), significant improvement was seen with the reduction of initial quadruple (or higher) pregnancies with a loss rate of 2.6%.¹¹ Another support for the use of embryonic aspiration is the potential risk of toxicity from the potassium chloride on the remaining fetuses. The fetus may be pushed away from the needle during the injection procedure causing the potassium chloride to diffuse into the amniotic sac and perhaps to other sacs causing harm to other fetuses.¹² A potential problem performing early fetal reduction is that the procedure may precede the phenomenon of the vanishing twin, in which one of the fetuses silently abort. But, researchers have noted that the vanishing twin phenomenon occurs infrequently, in only 9.8% of cases.¹³ Other methods that are occasionally employed in more advanced stages of pregnancy are air embolization and fetal blood removal, although many physicians reject these methods, claiming that they are more difficult to perform and carry more risk to all of the fetuses than embryo aspiration and potassium-chloride injection.¹⁴

An immediate issue facing the patient and physician regards the question of how many fetuses to abort. Because studies have shown that even twin pregnancy poses higher risks to both the mother and fetus than a singleton pregnancy, some physicians recommend fetal reduction to a singleton fetus.¹⁵ Other physicians recommend leaving twins to provide a "margin for error."¹⁶ The issue of reducing triplets to twins is similarly controversial. Increased risk of prematurity and low birth weight are associated with triplets when compared to twins. In a study comparing reduction of triplets to twins with non-reduced triplets the observed pregnancy loss was 25% for non-reduced triplets and 6.2% for triplets reduced to twins. The severe prematurity rate was 25% in non-reduced triplets and 4.9% in triplets reduced to twins, and the birth weight for non-reduced triplets was 1636 +/- 645 while it was 2381 +/- 602 for triplets reduced to twins.¹⁷ Yet, due to the relatively high chance of successful outcome with careful management and cesarean delivery, some physicians do not recommend reducing triplet pregnancies.¹⁸ There is almost no controversy as to the benefit of fetal reduction in quadruplet and higher gestations.¹⁹

Once the decision to reduce a multiple gestation is reached, additional questions arise. For example, when considering which fetuses to reduce, some physicians recommend selecting the fetuses according to the accessibility of the gestational sacs while others prefer selecting based on chromosomal analysis by chorionic villus sampling (CVS).²⁰ One recent study describes the preference for fetuses with fundal implantations on separate sides of the uterus to prevent competition and low implantation, thereby increasing the chance of positive pregnancy outcomes.²¹

History of Multifetal Reduction
In 1978, Swedish doctors published the first successful "selective termination" procedure. An earlier, non-published attempt at selective termination was performed in Denmark but ended in the spontaneous abortion of both twins three weeks after the procedure.²² The Swedish case presented with the pregnant mother of a child afflicted with Hurler’s disease who had undergone genetic analysis to determine if her twin fetuses were affected by the autosomal recessive trait. Results indicated that one twin was affected while the other was not. The parents considered terminating the pregnancy but requested an attempt at selective abortion. The procedure had not been successfully performed in the past, but the decision was made to attempt intracardial puncture following assessment of the potential risks. The procedure was successfully performed at 24 weeks gestation and the healthy infant was delivered at 33 weeks gestation.²³

Halakhic Dilemmas

Fetal Status
Orthodox Judaism has an extensive system of laws, referred collectively as "Halakha," that governs the life of the observant Jew. The primary sources for these laws are the Jewish Bible, the "Mishnah" the codified oral law, and the responsa literature of rabbinic authorities spanning millennia and continents.

To understand the issue of multifetal reduction from the perspective of Orthodox Jewish law, the dilemmas inherent in the procedure must be discussed. Furthermore, an operative definition of life must be proposed, although, it should be noted that the definitions are simplifications of more complex concepts. In one place in the Talmud, the fetus is described as "until forty (days) it is mere water,"²⁴ contending that the fetus is not considered to have human status until after forty days. Yet, its routine destruction is forbidden as the Talmud, in a different place, prohibits the destruction of semen.²⁵ Because of the inability for independent viability in utero, the Talmud elsewhere considers the fetus to be "a limb of its mother" and not a "nefesh," an independent human being.²⁶ In fact, a child achieves full human status only at thirty days postpartum, when it is established as a viable being.²⁷ These definitions will serve as a halakhic guideline further in the discussion.

From the perspective of legal liability, the fetus is not considered a full human being. In the case of unintentional abortion (with no mention of the gestational stage), it is stated in the book of Exodus, "If men strive, and hurt a woman with child, so that her fruit depart from her, and yet no further harm ensue: he shall be surely punished, according as the woman’s husband will lay upon him: and he shall pay as the judges determine."²⁸ The Twelfth Century physician and rabbinic authority, Maimonides further details the payment for the loss of the fetus, while not holding the person liable for murder.²⁹ Indeed, murder in Halakha is not indemnified by a monetary fine.We may understand from this that Maimonides does not view the fetus as a human being.³⁰

Although the fetus is not considered a full human being, it clearly has significant status in its own right, at least following forty days after conception. This is demonstrated by the allowance granted to violate the laws of the Sabbath to save a fetus.^31,32 However, Halakha does not consider the fetus an independent being which may be further understood from the law of a pregnant woman sentenced to be executed for a capital crime. In such a case, the sentence is not delayed until after she gives birth unless labor has begun.³³ The implications of these differing aspects regarding fetal status and abortion have lead to rabbinic controversy, with differing halakhic opinions and reasoning offered.

Halakha and Abortion
Controversy exists among rabbinic authorities regarding the issue of therapeutic abortion, while routine abortion is prohibited. The Mishnah states that if the woman’s life is endangered by the fetus, it should be aborted to save the mother’s life unless its head has already emerged: "If a woman is having difficulty in giving birth, one cuts up the fetus within her womb and extracts it limb by limb, because her life takes precedence over that of the fetus."³⁴ But, the Mishnah continues, once the head of the infant has emerged "one may not touch it, for one may not set aside one person’s life for that of another." For the most part, contemporary Halakha has adopted a conservative stand on the issue of abortion. In his article, "The Jewish Attitude Toward Abortion," Fred Rosner, a contemporary writer on Halakha and medicine, offers several possibilities as to why abortion, as a general rule, is halakhically prohibited. Firstly, Jewish law prohibits the destruction of semen. Additionally, if a woman miscarries after forty days, she is obligated to observe the laws of ritual impurity such as prescribed for a postpartum woman, and not as they apply to a menstruating woman. Thus, it appears that the abortion of the fetus places the mother in postpartum status similar to a woman who delivers a live infant. Yet, it should be noted that based on the Mishnah, if a woman miscarries within the first forty days, she is not halakhically considered postpartum.³⁵ He also brings the opinions of some modern rabbinic authorities that undergoing an abortion constitutes voluntarily placing oneself in danger, normally prohibited by Jewish law.³⁶ The late Rabbi Lord Immanuel Jakobovits, former chief rabbi of Great Britain, held that the permission for abortion cited above is only applicable in the case of the woman’s life being threatened by the fetus.³⁷ Today, this concept has been broadened to include a threat to the psychological health of the woman, though he adds that the threat must be both "probable and substantial to justify abortion."³⁸

Rodef
As a general rule regarding abortion, Halakha permits a therapeutic abortion in the situation where the mother’s life is threatened by the fetus, posing as a "rodef," or pursuer.³⁹ Halakha defines the pursuer as one who comes to kill another person.⁴⁰ In such a case, the Bible declares, an onlooker must take whatever precautions necessary to stop the pursuer even if it means killing him first.⁴¹ Thus, if a fetus threatens its mother’s life, is should be aborted to save the mother’s life.⁴² Maimonides considers the fetus to be a rodef that must be aborted: "… if a pregnant woman is having difficulty giving birth, the child inside may be excised, either by drugs or manually because it is regarded as pursuing her in order to kill her.⁴³ In multifetal gestation, where all the fetuses threaten each other resulting in reduced chance at survival, Halakha would consider the fetuses as each others’ pursuers.

It may be important to note that the Talmud, and subsequently Maimonides, refer to late abortion at the completion of pregnancy as they state that the woman is having difficulty at birth. However, in the case of multifetal pregnancy, the reduction is typically performed in the first trimester of pregnancy, when the fetuses are not viable outside the womb. Thus, these circumstances differ from those prescribed in the Talmud and in Maimonides’ compendium of Halakha, the Mishnah Torah. Furthermore, the fetuses threaten each other thereby rendering them each other’s pursuers.⁴⁴ If no medical attention is sought, the chance of fetal survival is reduced. By sacrificing some of the fetuses, others have a better chance at survival. Yet, the fetuses have equal halakhic status since none of them are yet a full human being, unlike the fetus’ halakhic status in comparison to its mother. Thus, it may be understood that multifetal reduction is only permissible in the event that the chance for the survival of the remaining fetus(es) is increased.

Decisions Associated with Reduction
At this point, the question arises as to which and how many fetus(es) to abort. One halakhic opinion holds that the number of fetuses to be reduced should be decided by the physician on purely medical grounds.⁴⁵ Some authorities that permit the procedure emphasize that the number of fetuses aborted must be minimized based upon the statistical probability of survival for the remaining fetus(es).⁴⁶ On this issue, there is a rabbinic consensus that the reduction should be done only on the minimal number of fetuses to ensure survival of "some fetuses."⁴⁷ By focusing on the probability of survival, the halakhic authorities are attempting to prevent fetal mortality and not necessarily fetal morbidity.

Selecting which fetuses to abort has been approached in various ways. Based on the biblical story of Jonah who was selected by lottery to be thrown overboard, one halakhic authority states that the choice should be made randomly by lottery as long as all of the fetuses are equal regarding location and health factors.⁴⁸ Other opinions hold that medical criteria or accessibility to the fetus(es) should guide the decision.⁴⁹ Previously mentioned is the approach to choose to leave the fetuses that do not share a placenta and are on opposite sides of the uterus to prevent competition between the fetuses and increase the likelihood of survival.⁵⁰ In any case, selecting which fetuses to abort based on location should be made in a manner that increases the chance of successful outcome.

One may ask, what if one or more of the fetuses present with a deformity or abnormality? Would it be permissible to choose to abort the affected fetuses? What if there is a gender preference? Normally, to selectively abort fetuses based on gender or a non-life-threatening abnormality is prohibited. The Talmud discusses the issue of deformity stating that a deformed fetus possessing two backs or two spinals cords "eino vlad," is not an offspring with regard to its mother’s postpartum purity status if she miscarries the deformed fetus. Yet, once the fetus has been born it earns the status of a human being.⁵¹ The Talmud uses the label "eino vlad" to indirectly indicate maternal postpartum status, while later commentators on the Talmudic source explain the label in fetal terms, that a deformed fetus is not considered a human being.

It has been suggested that a fetus with a life-threatening abnormality might be classified as a "treifah," a halakhic category used to designate an animal that may not be eaten because of a pre-existing condition that would have proved lethal. The Talmud suggests that in certain cases human beings may also possess such a status, which could have relevance in legal matters. Thus, one would incur no punishment by a court if he kills a person who would otherwise have soon died.⁵² The Meiri, an exegete in the Thirteenth Century, explains this controversial topic in his commentary on the Talmud: "…if within a group [of travelers] there is a treifah, then he may be given over [to brigands] so that they are not all killed."⁵³ Normally, a person must give up his own life rather than be responsible for another person’s death. In the case of multifetal pregnancy, without reduction all of the fetuses will probably die, rendering them all treifot. By aborting some of the fetuses there is chance for survival of those remaining. If among the fetuses there are some with an abnormality threatening their post-uterine life, it appears permissible to selectively abort the affected fetuses to prevent the abortion of healthy fetuses. Differing opinions are often cited regarding the general issue of aborting an abnormal fetus, independent of the total number of fetuses. On one side, some rabbinic authorities prohibit the abortion of an abnormal fetus such as may result from maternal exposure to German measles or thalidomide during pregnancy.⁵⁴ A different halakhic opinion permits the abortion of a fetus with Tay-Sachs in the first trimester.⁵⁵ In the specific case of multifetal reduction, one rabbinic authority permits the reduction of abnormal fetuses to ensure the safe delivery of healthy fetuses, thereby preventing premature delivery and its health implications.⁵⁶

Conclusion

Without medical intervention, there is a high probability that a multigestational pregnancy will not have a successful outcome. The multiple fetuses threaten each others’ survival and endanger the mother as well, possibly rendering them the status of rodef. In addition, given their reduced probability of surviving, the fetuses might be considered treifot under Jewish law. There is halakhic preference to performing an early fetal reduction prior to forty days of gestation. Some rabbinic authorities hold that only (random) non-selective reduction may be performed to facilitate the survival of the remaining fetus(es). Others permit selective reduction under certain circumstances such as fetuses carrying the Tay-Sachs gene, although selective implantation of embryos is clearly preferable.

In their published opinion, the ethics committee of the American College of Obstetricians and Gynecologists recommend preventing multigestational pregnancy during the hormonal regulation, conception and implantation stages of fertility treatments. The performance of multifetal reduction should not be routine, but rather viewed as treatment for a problem that has resulted from fertility treatment. As a standard element of fertility treatments, the risks, benefits, and alternatives to the treatments under discussion should be detailed.⁵⁷ Addressing the bioethics of multifetal reduction, Drs. Mark Evans, Neil Wenger and Alan DeCherney recommend that physicians carefully analyze from an ethical perspective each case of multifetal gestation.^58,59 For the couple concerned with Halakha, complementary analysis by a rabbinic authority is in order to reach the most appropriate decision for each couple as they encounter the dilemmas of multifetal reduction.

For personal use. Only reproduce with permission from SIEP.

References

1. Wenger NS, DeCherney AH. An ethical approach to assisted reproduction. Reproductive Technologies 2000;10(4):178-183

2. Brambati B, Tului L, Guercilena S. Genetic analysis prior to selective fetal reduction in multiple pregnancy: technical aspects and clinical outcome. Human Reproduction 1995;10:818-825

3. Evans MI, Goldberg JD, Horenstein J, Wapner RJ, Ayoub MA, Stone J, Lipitz S, Achiron R, Holzgreve W, Brambati B, Johnson A, Johnson MP, Shalhoub A, Berkowitz RL. Selective termination for structural, chromosomal, and mendelian anomalies: international experience. American Journal of Obstetrics and Gynecology 1999;181:893-897

4. Ibid

5. Antsaklis AJ, Drakakis P, Vlazakis GP, Michalas S. Reduction of multifetal pregnancies to twins does not increase obstetric or perinatal risks. Human Reproduction 1998;14:1338-1340

6. Evans MI, Fletcher JC, Zador IE, Newton BW, Quiqq MH, Struyk CD. Selective first-trimester termination in octuplet and quadruplet pregnancies: clinical and ethical issues. Obstetrics and Gynecology 1988;71:289-296

7. Evans MI, Kramer RL, Yaron Y, Drugan A, Johnson MP. What are the ethical and technical problems associated with multifetal pregnancy reduction? Clinical Obstetrics and Gynecology 1998;41:47-54

8. Evans MI, Dommergues M, Timor-Tritsch I, Zador IE, Wapner RJ, Lynch L, Dumez Y, Goldberg JD, Nicolaides KH, Johnson MP, Golbus MS, Boulot P, Aknin AJ, Monteagudo A, Berkowitz RL. Transabdominal versus transcervial and tranvaginal multifetal pregnancy reduction: international collaborative experience of more than one thousand cases. American Journal of Obstetrics and Gynecology 1994;170(3):902-909

9. Coffler MS, Kol S, Drugan A, Itskovitz-Eldor J. Early transvaginal embryo aspiration: a safer method for selective reduction in high order multiple gestations. Human Reproduction 1999;14:1875-1878

10. Coffler MS, Kol S, et al., 1999

11. Ibid

12. Mansour RT, Aboulghar MA, Serour GI, Sattar MA, Kamal A, Amin YM. Multifetal pregnancy reduction: modification of the technique and analysis of the outcome. Fertility and Sterility 1999;71(2):380-384

13. Coffler, 1999

14. Evans MI, Fletcher JC, et al., 1988

15. Kiely JL, Kleinman JC, Kiely M. Triplets and higher-order multiple births. American Journal of Diseases in Childhood 1992;146:862-868

16. Evans MI, Fletcher JC, et al., 1988

17. Yaron Y, Bryant-Greenwood PK, Dave N, Moldenhauer JS, Kramer RL, Johnson MP, Evans MI. Multifetal reductions of triplets to twins: comparison with nonreduced triplets and twins. American Journal of Obstetrics and Gynecology 1999;180:1268-1271

18. Lipitz S, Reichman B, Paret G, Modan M, Shalev J, Serr DM, Mashiach S, Frenkel Y. The improving outcome of triplet pregnancies. American Journal of Obstetrics and Gynecology 1989;161:1279-1284

19. De Catte L, Camus M, Bonduelle M, Liebaers I, Foulon W. Prenatal diagnosis by chorionic villus sampling in multiple pregnancies prior to fetal reduction. American Journal of Perinatology 1998;15:339-343

20. Ibid

21. Evans MI, Fletcher JC, et al., 1988

22. Kerenyi TD, Chitkara U. Selective birth in twin pregnancy with discordancy for Down’s syndrome. The New England Journal of Medicine 1981;304:1525-1527

23. Aberg A, Mitelman F, Cantz M, Gehler J. Cardiac puncture of fetus with Hurler’s disease avoiding abortion of unaffected co-twin. Lancet 1978;2:990-991

24. Yebamot 69b

25. Niddah 13a. (Based on the Biblical story of Onan’s punishment in Genesis 38:10)

26. Chullin 58a

27. Rosner F. The Jewish attitude toward abortion. Tradition 1968;10(2):48-71

28. Exodus 21:22

29. Hilkhot Hovel Umazik 4:1

30. Rosner F, 1968

31. Arakhin 7b

32. Neuwirth YY. Shemirath Shabbath Kehilchata [Observance of Sabbath according to the Laws]. Jerusalem:Feldheim Publishers, Vol. 1, Chapter 36(2), 1989

33. Arakhin 1:4

34. Ohaloth 7:6

35. Niddah 3:7

36. Rosner F, 1968

37. Rosner F, 1968

38. Eisenberg, D. Multifetal pregnancy reduction in halacha. At the Website for the Institute for Jewish Medical Ethics of the Hebrew Academy of San Francisco, 2000

39. Zilberstein Y, Osher P. Multifetal Reduction. Assia, Tevet 5749;12:1-2

40. Sanhedrin 72a

41. Rashi on Exodus 22:1 (Further discussed in the Talmud, Berakhot 58a.)

42. Ohaloth 7:6

43. Hilkhot Rotzeach 1:9

44. Eliyah M. Destruction of eggs and multifetal reduction. Tehumim 1990;11:272-273

45. Eliyahu M., 1990

46. Zilberstein, 5749

47. Bleich JD. Pregnancy reduction. Tradition 1995;29(3):55-63

48. Mehlman, Y. Multi-fetal pregnancy reduction. Journal of Halacha and Contemporary Society 1994;27:35-68

49. Ibid

50. Evans MI, Fletcher JC, et al., 1988

51. Bekhorot 43b

52. Mehlman Y, 1994

53. Meiri on Sanhedrin 72b

54. Bleich JD. Abortion in Halakhic Literature. Tradition :72-120

55. Tzitz Eliezer. Responsa of Rabbi Judah Eliezer Waldenberg, 1975

56. Halevi HD. Responsum to Richard Grazi. Assia Tevet 5749;12:3-4

57. ACOG Committee Opinion. Nonselective embryo reduction: ethical guidance for the obstetrician-gynecologist. International Journal of Gynecology and Obstetrics 1999;65:216-219

58. Fletcher JC, Wertz DC. Ethics and decision-making about diagnosed fetal anomalies. Reproductive Risks and Prenatal Diagnosis. Evans MI (ed.) Appleton & Lange:Norwalk, 1992, 294-297

59. Wenger NS, DeCherney AH, 2000