SURVIVAL
RATES
IN
RH
SENSITIZATIONS:
I 40
Interrupted
Versus
I 4 I
Uninterrupted
Pregnancies
Thomas R. Boggs, Jr., M.D.
Departments of Pediatrics and Obstetrics and Gynecology, School of Medicine, University of
Pennsylvania, and the Division of Obstetrics and Gynecology of Pennsylvanis Hospital, the Department
of obstetrics and Gi/liecOlOgy of the hospital of the Unicersittj of Penn.st,lcania 072(1 the Section on
Pediatrics of Tile Pennsylcania Hospital
PEnIATRIcs, May 1964
I
1963 this writer and co-workerspub-. lished data which suggested that early termination had a place in the management
of selected pregnancies associated with
sensitization to the Rh factor. Our experi-ence further indicated tilat the outcome of
prior pregnancies was the most important
factor governing the selection of cases. As
a result, we had begun to employ tile
ap-proach of interrupting selected pregnancies with increasing frequency. This paper com-pares the results achieved in 140 inter-rupted pregnancies with those achieved in 141 pregnancies which were allowed to terminate spontaneously over the time pe-nod 1957 through 1962.
APPROACH
During this period 285 erythroblastotic infants were delivered from 281
Rh-nega-tive sensitized women at the Pennsylvania
Hospital and the Hospital of the University
of Pennsylvania. There were 4 sets of twins.
All 8 twins survived and for the sake of
simplicity are treated as single cases. In
order to effect the most meaningful
corn-parison possible, these 281 pregnancies
were grouped according to pregnancy risk.
Pregnancy risk was defined as “high,”
“in-termediate,” or “low.” High risk pregnancies were those occurring in women who ilad had a previous stillborn Rh erythroblastotic infant or one who was liveborn with
hy-drops * Intermediate risk
pregnan-cies were tilose occurring in women who
had had a Ir’\’ius erythrol)lastotic infant
I)llt the infant was neither stillborn nor
iiy-dropic. Low risk pregnancies were illitial
sensitizations . Interru1)ted pregnancies were
those terminated by induction or cesarean section before the spontaneous onset of labor and with the fetus considered to be alive.
Uninterrupted cases were those which were
allowed to go into labor spontaneously and
those pregnancies termrnated by induction
or cesarean section after the diagnosis of an
intrauterine death.
RESULTS
The results of our experience with high risk pregnancies are presented in Table I. The pregnancies are arranged according to gestational age at delivery and according
to whether interrupted or uninterrupted.
Whether or not the pregnancy resulted in the l)irth of a liveborn infant who
sur-vived, a stillborn infant, or a liveborn
in-fant who suffered a neonatal death is
shown. The cause of the neonatal deaths is also given. Tables II and III present iden-tical data for the intermediate and low risk
pregnancies. Tile data presented in Tables
I, II, and III are condensed and presented
again in Table IV.
In scanning Tables I, II, and III, it should be noted that interruption of a
preg-nancy prior to 34 weeks was attempted in
high risk pregnancies only and then in just 6 instances. Only 2 infants survived. Tile
0 Marked edema with ascites.
(Submitted May 6; revision accepted for publication October 1 1, 196.3.)
No. of Surr. Still- Neo.
Preg. Infants !?irlh.Y Deal h.s
Cause of Deal/i vo.of Preg. Sort’. Still-Infants Birth.9 Neo. Thaths Cause of Death Wee1s Gest. 30 1 31 0 32 3 33 34 35 4 36 0 37 3 38 3 39 ‘2 40 0 Total ()
(‘ii inkrru pled
1I1drops
2 IIv(lrops 1Hvdrops
1H.M.l).
1 Ilvdrops Iulerru jiled
0 0 0 0 I 0 1 0 1 0 2 0 0 0 3 0 3 0 l 0 0 0 13 0 1 0 0 0 0 0 0 3 4 0 1 0 ‘1 17 0 0 0 0 0 0 0 0 0 3 0 3 0 1 ‘2 0 0 0 H 0 0 0 0 0 0 0 0 3 I 1[drops I Ilydrops I Hydrops
ilydrops = generalized edema and ascites.
H.M.D. = ilyaline Menibrane l)isease.
.\O. of Sun. Still- .‘seo. Preg. Infants Births Deaths
Cause of \O. of Suri.
Still-Death Preg. Infants Births
Veo. Death.3 (‘au.9e of Death Weeks Gest. 30 Si 33 34 ‘35 36 37 38 39 40 Un interrupted 0 0 0 0 I.) 10 7 14 6 3 Interrupte(l 0 0 0 0 0 0 0 0 1 0 5 0 10 0 7 0 14 0 6 0 ‘3 0 0 (I 0 0 1 0 0 0 0 U (I 1llv(lroj)s 0 0 0 0 1 5 9 ‘2 0 3 3 7 3 3 9 5 1 0 0 3 1 0 1760 c;rariss I Ilydrops 1 Hemorrh. 1)iathesis 0 0 0 0 0 0 1 0 0 0
Total 47 46 0 I 43 17 3
TABLE I
Ru SENsITIz.TIoNs: P.11 AND H.U.P., 1957-961, 37 HIGH RISK PREGNANCIES
unsatisfactory results encountered here are
interpreted by us as indicating that
inter-ference at 33 weeks gestation or less offers little hope of success. For the same reason,
we are of the opinion tilat the relative
merits of early termination should he
judged by a comparison of those preg-nancies of more than 33 weeks duration. It should also be noted that among those
pregnancies interrupted after 33 weeks
ges-tation tllere were only 2 neonatal deaths that could possibly be attributed to the
in-TABLE II
TABLE III
Ru SENSITIZATIONS: P. H. AND H. U. P., 1957-1962, 154 Low RISK PREGNANCIES
Weeks Gent. No. of Preg. Surv. Infants Still-Births \reo Deaths Cause of Death No of Preg. Surr. Infant Still-Births Xeo. Death (aus of Death 30 31 3 33 34 35 36 37 38 39 40 Total interrupted Uninterrupted 0 0 0 0 1 1 5 14 13 17 73 0 0 0 0 1 1 3 14 2 13 17 71 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 2 1 HJ%1.D. 1Hemorrh. Diathesis 1 0 3 0 3 0 7 8 17 10 32 81 0 0 3 0 2 0 3 6 15 10 32 71 0 0 0 0 0 0 4 2 2 0 0 8 1 0 0 0 1 0 0 0 0 0 0 si 1-1’2’37 Grams 1 Hydrops
terruption of the pregnancy. Both infants as compared to 22% (2/9) in the
uninter-died from hyaline membrane disease. One rupted pregnancies. Tile difference is sig-infant was among the 34 delivered by ce- nificant. After 33 weeks, the Chi-Square sarean section and one was among the 100 Value is 5.0. With one degree of freedom, infants liveborn following the induction of the significance is at the .05 level.
labor. Of the interrupted intermediate risk From Tables I and IV it will be seen pregnancies (Tables II and IV) 98% (46/47) that 65% (13/20) of the interrupted high resulted in a surviving infant as compared risk pregnancies resulted in a surviving in- to 53% (23/43) among the uninterrupted.
fant as compared to 12% (2/17) of the un- After 33 weeks tile comparison was : 98% interrupted pregnancies. After 33 weeks (46/47) to 70% (23/33). The difference is gestation, 79% (11/14) of the interrupted highly significant. After 33 weeks, the Chi-pregnancies resulted in a surviving infant Square Value is 10.7. With one degree of
TABLE IV
RH SENSITIZATIONS: P. H. AND H. IT. P., 1957-196’2, INCIDENcE OF SURVIVING INFANTS
Pregnancy Risk Interrupted Pregnancies Uninterru/)ted Pregnancies
High Intermediate Low High Intermediate Low
All8I Pregnancies
65%(13/’20) 98% (46/47) 97% (71/73) u%( sl/17) 53% (si3/4’3) 88% (71/81)
253 Pregnancies of 34 weeks
gestation or more
79% (1 1/14) 98% (46/47)
97% (71/73)
All Pregnancies
Interrupted Pregnancies
Uninterrupted Pregnancies
ARTICLES
TABLE V
RH SENSITIZATIONS: P. H. AND H. U. P., 1957-196, DISTRIBUTION OF STILLBIRTHS AND HYDROPIC LIVEBIRTHS
High risk pregnancies Inter. risk pregnancies Low risk pregnancies
All pregnancies
57% (21/37)
22% (20/90)
6% (10/154)
18% (51/281)
30% (6/20) 88% (15/17)
2% (1/47) 44% (19/43)
1% (1/73) 11% (9/81)
6% (8/140) 31% (43/141)
freedom, the significance is at the .01 level.
Of the interrupted low risk pregnancies (Tables III and IV) 97% (71/73) resulted in a surviving infant as compared to 88% (71/ 81) of the uninterrupted pregnancies. After 33 weeks, the percentages remain un-changed: 97% (71/73) vs 88% (68/77). The differences here are not significant.
There were, in this series of 281 Rh erythroblastotic infants, 37 stillbirths, 14 infants liveborn with hydrops fetalis, and 230 infants liveborn without hydrops fetalis. Two of the 14 hydropic infants survived and 12 suffered a neonatal death. The dis-tribution of these 37 stillborn and 14 hy-dropic liveborn infants between the preg-nancies of differing degrees of risk is given in Table V. All cases considered, the mci-dence of stillbirths and hydropic livebirths was 57% (21/37) among high risk, 22% (20/ 90) among intermediate risk, and 6% (10/ 154) among low risk pregnancies. Among uninterrupted pregnancies, the distribution was: high risk pregnancies 88% (15/17),
in-termediate risk pregnancies 44% (19/43),
and low risk pregnancies 11% (9/81). Table VI presents the survival rate among liveborn infants grouped by gesta-tional age. No consideration is given to pregnancy risk or whether the pregnancy
was interrupted or not. There were 244
liveborn infants; 93% (226) survived: 96% (221/230) born alive after 33 weeks, 98% (205/209) born alive after 35 weeks, and 99% (152/153) born alive after 37 weeks survived.
COMMENT
We are pleased with the results just pre-sented and believe that interruption of care-fully selected pregnancies has a role in the management of Rh sensitizations. However, because of the many variables involved, it it not easy to assess the relative merits of this approach even in a reasonably sized case experience such as this. Therefore, it is important to underscore certain aspects of this report.
First, this is a retrospective study of pregnancies known to have resulted in the births of erythroblastotic infants. No con-sideration has been given to the many dif-ficulties encountered in attempting to deter-mine, prior to delivery, whether a repeat pregnancy in a previously sensitized woman is, or is not, associated with an Rh positive fetus. We have guessed wrong in these sit-uations and have been chagrined, after in-terrupting a pregnancy, to discover tile in-fant to be a normal Rh negative baby.
TABLE VI
RH SENSITIZATIONS P. H. AND H. U. P., 1957-1962, SURVIVAL RATES AMONG
LIVEBORN INFANTS BY GESTATIONAL AGE
All Infants Infants of Weeks
or More
Infants of 36 Weeks or More
Infants of 38 Weeks or More
226/244
93%
221/230 96%
205/209
98%
762
Spectrophotometric analysis of amniotic fluid should prove helpful here.
Second, all the stillbirths are listed with the uninterrupted cases. This is appropri-ate because all the fetuses were correctly diagnosed as having suffered an intrau-terine death before any attempt was made to terminate the pregnancies. Nevertileless, this approach to the grouping of our case material strongly weighs the scales in fa-vor of interruption.
Third, it may be that an element of good fortune contributed to our low incidence of hyaline membrane disease.
Four, case selection was not accom-plished by random selection. Moreover, the timing of an interruption, while generally following a preset pattern, did not always adhere to this pattern. Stated slightly dif-ferently, interruption was practiced more frequently and generally at an earlier ges-tational age in high risk as compared to low risk pregnancies but alternate higher risk cases were not interrupted or allowed to terminate spontaneously and a consistent timing of the interruption schedule was not adhered to. Such disciplines would have rendered the data here presented far easier to interpret.
In spite of the foregoing reservations, other aspects of our experience strongly support selective interruption. These may be listed as follows : (1) A high survival rate among liveborn infants, even among those of lower gestational age. Of those infants born alive after 33 weeks gestation 96% sur-vived. (2) A low incidence of the respira-tory distress syndrome among our inter-rupted cases. Only 1 infant among 34 de-livered by cesarean section and only 1 among 100 infants liveborn following the induction of labor died of hyaline mem-brane disease. (3) A significant reduction in perinatal loss in high and intermediate risk
pregnancies of a gestational age of more than 33 weeks which were interrupted as compared to that ellcOuntered in high and intermediate risk pregnancies of 33 weeks gestation or more which were allowed to terminate spontaneously. This reduction in
perinatal loss resulted from tile avoidance of stillbirths and livebirths associate(l with hydrops fetalis.
Therefore, we plan to continue to inter-rupt pregnancies associated witil Rh
sensi-tizations as follows : (1) High risk preg-nancies, believed to be associated with an Rh positive fetus, will be interrupted at 34-35 weeks. (2) Intermediate risk pregnan-cies, believed to he associated with an Rh positive fetus, will he interrupted at 36-37 weeks. (3) Low risk pregnancies will 1)e in-terrupted at 38 weeks providing the mother
is a good candidate for induction. If not, the pregnancy will be allowed to terminate
spontaneously. (4) Any pregnancy associated
vitii the development of polyhydramnios will be interrupted at once providing the gestational age is 33 weeks or more. Inter-ruption prior to this date is almost always associated with a neonatal death. (5) The method of interruption will be at the dis-cretion of the obstetrician.
SUMMARY
The comparative results achieved in 140
interrupted and 141 uninterrupted
preg-nancies associated with an Rh sensitization are presented. The data are interpreted as
indicating that early termination of selected pregnancies has merit. A program of selec-tion based on maternal history is presented.
REFERENCE
1. Boggs, T. R., Jr., M.D., Moore, J., M.D.,
Fields, H., M.D., et a!.: Early termination of
pregnancy in Rh sensitization. Obst. Cynec.,
