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E L S E V I E R Eu ro p e a n Jo u rn a l o f Ob st et ri cs & Gy n e c o l o g yand Reproduct ive Bio logy 68 (1996) 53-58 . . o , o . . . . . . . J , o , .

A n a e m i a i n p r e g n a n c y is t h e c u r r e n t d e f i n it io n m e a n i n g f u l?Terence T. Lao*, Ting-Chung Pun

Department of Obstetrics and Gynaecology, The University of H ong Kong, T san Y uk and Q ueen Mary H ospitals, 30 Hospital Road Hong Kong,Hong KongReceived 27 Nove mb er 1995; rev ised 15 Apri l 1996; accep ted 8 May 1996

A l ~ ' K tObjective: To determine i f the curren t defini t ion of antenata l anaemia (haemoglobin < 10 g/dl) has any cl inical s ignif icance.Study design: A retrospect ive study o n al l s ingleton del iveries ove r a 3-year period in tw o teaching hospi tals und er on e universitydepar tment was conducted by the ex t rac t ion of da ta f rom a com puter da tabase . The m ajor pregnancy compl ica t ions and per ina ta loutcom e were compared be tween m others wi th a nd w i thout anaemia and adjus ted for par i ty . Results: The incidence o f m ult ipari tywas signif icant ly higher in the 817 anaemia pat ients com pared to the 10 125 non-anaemia pat ients , but th ere was no difference inthe incidence of other m ajor anten atal complicat ions, type of labo ur or m ode o f del ivery, incidence of preterm del ivery, or perina talmortal ity o r morbidi ty, af ter adjusting for pari ty. Am ong the anaemia pat ients , those with thalassaemia t rai t (54.8%) had asignif icantly higher incidence of gestational glucose intolerance but the incidences of o ther com plications a n d t h e perinatal outcomewere similar to the i ron deficiency pat ients . Conclusion:An tenatal anaemia, defined as a maternal haemoglobin of < 10 g/dl , doesnot adversely affect pregnancy ou tcom e. This raises the quest ion o f whether the diagnosis o f anaemia should b e redefined.

Keywords: Antenatal anaem ia; Iron deficiency; Thalassaemia t rai t ; Pregnancy ou tcom e

1 . I n t r o d u c t i o n

A n a e m i a i s c o n s i d e r e d t h e c o m m o n e s t m e d i c a l d i s -o r d e r i n p r e g n a n c y , t h e i n c i d e n c e in d e v e l o p e d c o u n t r i e sb e i n g a r o u n d 5 % [ 1 ]. H i s t o r i c a l ly , i t h a s b e e n a s s o c i a t e dw i th a d v e r s e p r e g n a n c y o u t c o m e s u c h a s p r e t e r m b i r th ,l o w b ir t h w e i g h t a n d i n c r e a s e d p e r i n a t a l m o r t a l i t y [ 2 - 5 ] .H o w e v e r , th e r e v i ew o f H e m m i n k i a n d S t a r f ie l d [ 6] h a ds h o w n t h a t i r o n s u p p l e m e n t a t i o n h a d n o s i g n i f i c a n ti m p a c t o n p r e g n a n c y o u t c o m e , w h i c h w a s a f f e c t e dm a i n l y b y o t h e r r i s k f a c t o r s . F u r t h e r m o r e , t h e r e i s i n -c r e a s i n g e v i d e n c e f r o m d e v e l o p e d c o u n t r i e s t o i n d i c a t et h a t a h i g h h a e m o g l o b i n m a y b e a s b a d a s , o r e v e nw o r s e t h a n , a l o w h a e m o g l o b i n , f o r t h e i n c id e n c e o f lo wb i r t h w e i g h t a n d p e r i n a t a l m o r t a l i t y a r e i n c r e a s e d w i t hi n c r e a s e d h a e m o g l o b i n e v e n i n n o r m a l p r e g n a n c i e s[ 7 - 1 8 ]. F r o m t h es e r e p o rt s , t h e p r e g n a n c y o u t c o m e w a so p t i m a l w h e n t h e h a e m o g l o b i n l e v e l w a s b e t w e e n 9 a n d1 3 g / dl [ 7 - 1 5 , 1 8 ] . S i n c e t h e n o r m a l c u t o f f f o r m a t e r n a l

* Correspo nding au thor. Tel .: +852 2589 2221; fax: +852 2517 3278 .

h a e m o g l o b i n l e v e l r e c o m m e n d e d b y t h e W o r l d H e a l t hOr g a n i s a t i o n ( W H O ) i s 1 1 g / a l l [ 19 ], b e l o w w hi c h t hem o t h e r i s c o n s i d e r e d a n a e m i c , i t i s a p p a r e n t t h a t a s ig -n i fi c an t p r o p o r t i o n o f th e ' a n a e m i c ' m o t h e r s w o u l d a l soh a v e o p t i m a l p r e g n a n c y o u t c o m e . T h i s t h e r e f o r e c a l l si n t o q u e s t i o n t h e v a li d i t y o f t h e c u r r e n t W H O d e f i n i t i o no f t h e d ia g n o s i s o f a n a e m i a i n p r e g n a n c y .

I n T s a n Y u k a n d Q u e e n M a r y H o s p i t a l s , w e h a v eb e e n u s i n g t h e h a e m o g l o b i n l e v el o f < 1 0 g/ d l t o d i a g -n o s e a n t e n a t a l a n a e mi a [ 2 0 ] , a l e v e l t ha t i s e v e n l o w e rt h a n t h e W H O r e c o m m e n d a t i o n . D e s p i te a n o v e r a l l i n-c i d e n c e t h a t i s h i g h e r ( 9% v s . 5 % ) t h a n t h a t q u o t e d [ 1] ,i t d i d n o t a p p e a r t o u s t h a t m o t h e r s w i t h a n a e m i a f a r e dw o r s e t h a n t h o s e w i t h o u t. W e h a v e t h e r e f o r e c o n d u c t e da r e tr o s p ec t iv e s tu d y c o m p a r i n g t h e p r e g n a n c y c o m -p l i c a t i o n s a n d p e r i n a t a l o u t c o m e i n s i n g l e t o n p r e g n a n -c ie s w i t h a n d w i t h o u t a n t e n a t a l a n a e m i a m a n a g e d o v e ra 3 - y e a r p e r i o d t o d e t e r m i n e w h e t h e r t h e c u r r e n t p r a c -t ic e o f d i a g n o s in g a n t e n a t a l a n a e m i a u s i n g a n a r b i t r a r yc u t - o f f v a l u e ha s a n y c l i n i c a l s i g n i f i c a n c e . M u l t i f e t a lp r e g n an c i es w e r e e x c lu d e d f r o m o u r s t u d y e v e n t h o u g h

0301-2115/96/$15.00 1996 Elsevier Science Ireland L td. All rights reservedP II S 0 3 0 1 -2 1 1 5 (9 6 )0 2 4 7 9 -7

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54 T. T. Lao, T.- C Pun /Euro pean Journal of Obstetrics & Gynecology and Reproductive Biology 68 (1996) 53-5 8

the incidence of anaemia is higher in this group, becausethe majority of the pregnancy complications in multi-fetal pregnancies could be related to, or accounted for,by the multifetal pregnancy itself, so that the resultswould be difficult to interpret.2 . M a t e r i a l s a n d m e t h o d s

The Obstetric Units of Tsan Yuk and Queen MaryHospitals are under the Department of Obstetrics andGynaecology of the University of Hong Kong, and areregional tertiary centres. The population we serve andthe antenatal management of our patients have beenreported before [20]. The antenatal care, management ofcomplications, labour and delivery, are according toestablished practice. Routine multivitamin and iron sup-plements (with 29 mg of elemental iron in a proprietarypreparation) is given to all mothers. The information ofeach pregnancy that was delivered in our hospital wascoded and entered into a computer database.

All antenatal patients have blood drawn for the esti-mation of haemoglobin and measurement of the meancell volume (MCV) at the time of booking. The measure-ment of the MCV is used in the screening of both ot and

thalassaemia carriers to whom prenatal diagnosiscould be offered should the diagnosis be confirmed bya follow-on haemoglobin electrophoresis test. The ma-ternal haemoglobin is estimated again at least once atthe beginning of the third trimester, or at any time whenclinical features suggest the development of anaemia.Antenatal anaemia is diagnosed when the lowest haemo-globin level falls below 10 g/dl at any time before deliv-ery. All patients with antenatal anaemia have their ironstatus examined and the cause of the anaemia classified,which is coded in the final summary for entry into ourobstetric database.

T a b l e IM a t e r n a l d e m o g r a p h i c d a t a i n t he a n a e m i a a n d n o n - a n a e m i a p a t i e n t s(%)

A n a e m i a g r o u p N o n - a n a e m i a g r o u pn = 8 1 7 n = 1 0 1 2 5

M a te r n a l a g e i n y e a r s 2 8 . 4 5 . 2 2 8 . 2 5 . I( m e a n S . D . )

M u l t i p a r a s 4 6 4 ( 5 7 . 0 )* 5 1 9 0 ( 5 1 . 0 )Sm oker s 21 (3 .0 ) 258 (3 .0 )* P < 0 . 0 1 .

In this retrospective study, the data on all motherswith singleton pregnancies who delivered betweenJanuary 1990 and December 1992 were retrieved. Theones with the coding for antenatal anaemia were iden-tified and the incidence o f major maternal complicationsand the pregnancy outcome in this group was comparedwith the remaining mothers who did not have anaemia,as well as between mothers with iron deficiency andthalassaemia trait. Statistical analysis is performed withthe chi-square test and Student's t-test where appro-priate.3 . R e s u l t s

Of the 10 942 singleton pregnancies delivered duringthe study period, 817 (7.5%) were diagnosed to haveantenatal anaemia. Among these 817 patients, 448(54.8%) had either or- or ~-thalassaemia trait, whileanother 21 (2.6%) had iron deficiency in addition tothalassaemia trait. The remaining 348 (42.6%) wereclassified as iron deficiency. In the whole group, thelowest haemoglobin was between 8 and 8.9 g/dl in 128(15.7%) patients, and between 7and 7.9 g/dl in 20 (2.4%)patients. Another five (0.6%) patients had the lowest

T a b le 2A n t e n a t a l c o m p l i c a t i o n s i n t h e a n a e m i a a n d n o n - a n a e m i a p a t i e n t s a d j u s t e d f o r p a r i t y

N u l l i p a r a s M u l t i p a r a sC o n t r o l s A n a e m i a C o n t r o l s A n a e m i an = 4935 n = 353 n = 5190 n = 464

D ia b e t e s m e l l i t u sPre -ex is t ing 0 .1 0 0 .3 0 .2I G T ( W H O c r i t e r ia ) 5 . 2 4 . 0 7 . 2 8 . 8G e s t a t i o n a l 0 . 7 0 . 6 0 . 8 0 . 6

V e n e r e a l d i s e a s e s 0 . 9 0 . 3 0 . 4 0 . 4M o n i l i a l i n f e c t i o n I . 3 I . 8 8 . 9 I 1 . 2O t h e r v a g i n a l i n f e c t i on s 3 . I 5 . I 2 . 2 4 . IP r e g n a n c y - i n d u c e d h y p e r t e n s i o n 6 . 3 6 . 8 2. 9 3 . 0C h r o n i c h y p e r t e n s io n 0 . 8 0 . 8 1 .5 0 . 6P l a c e n t a p r e v i a 0 . 6 0 . 6 1 .0 0 . 9A c c id e n t a l h e m o r r h a g e 2 . 0 1 .4 2 . 3 1 .3R e su l t s e x p r e s se d i n p e r c e n t a g e s . I G T , im p a i r e d g lu c o se t o l e r a n c e .* P < 0 . 02 5 c o m p a r e d w i t h m u l t i p a r o u s c o n tr o l s .

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T.T. L ao, T .-C Pun/European Journal of O bstetrics & Gynecology and Reproductive Biology 68 (1996) 5 3-5 8T a b l e 3L a b o u r a n d d e l i v e ry i n t h e a n a e m i a a n d n o n - a n a e m i a p a t i e n t s a d j u s t e d f o r p a r i ty

55

N u l l i p a r a s M u l t i p a r a sC o n t r o l s A n a e m i a C o n t r o l s A n a e m i an = 4935 n = 353 n = 5190 n = 464

I n d u c t i o n o f l a b o u r 1 4 . 5 1 3 . 0 7 . 6 7 . IA u g m e n t a t i o n o f l a b o u r 3 9 . 3 4 0 . 2 3 I . 3 2 . 9D e l i v e r yIns t ru me ntal 24 .6 22 .9 7 .6 9 .7

Breech 1 .6 0 .8 1 .8 0 .6Elect ive C sect io n 2 .4 2 .3 7 . I 6 .7Em ergen cy C sect ion 13 .0 11 .6 6 .6 8 .0

C o m p l i c a t i o n sP r o l a p s e d c o r d 0 . 2 0 . 6 0 . 3 0 . 9P o s t p a r t u m h e m o r r h a g e

Pr im ary 3 .0 2 .5 3 .2 4 .7S e c o n d a r y 0 . 3 0 . 6 0 . 2 0 . 4

R e t a i n e d p r o d u c t s 0 .4 0 .6 0 .6 1 .3Ute r ine a ton y 1 .7 0 .8 2 .1 1 .7P o s t p a r t u m p y m x i a 4 .0 4 .5 2 .2 2 .2

R e s u l t s e x p r e s s e d i n p e r c e n t a g e s .

h a e mo g lo b in , b e tw e e n 6 . 5 a n d 6 . 9 g /d l . N o p a t i e n t h a da h a e m o g lo b in < 6 . 5 g /d l .

There was no d ifference in the maternal age or in thein c id e n c e o f s mo k e r s b e tw e e n p a t i e n ts w i th a n d w i th o u ta n a e mia (T a b le 1 ) , b u t th e r e w e r e mo r e mu l t ip a r o u spat ients in the anaemia group (57.0% vs. 51 .0%, P