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ti 11 716 OBSTETRICAL AND GYNECOLOGICAL SURVEY C.iGARETTE SMOKING ' AND' FETAL BREATHING ' MOVEMENTS F. A: M.a\NI1+1G AND C. FEYEFtABEt1D The Nuffreld Institute for -tYedical Rssearch, Univenityof O,rford. Ohford„E,tgJand' BriL J. Obsr. & Gynec. 83: 262. 1976I The: present, observations: were undertaken too study the effect' ini high risk pregnancies and! to detetminethe factor in cigarette smoke responsible for the depression off fetal breathing. Continuous records of fetal chest wa1C' move• ments in utero were made using the A-scan ultrasound method. Fetal breat!hing movements were measured before and after smoking two consecutive tobacco cigarettes irr. 19 women with notmal' pregna'ncies; 10 with prceclampsia; f2'with diabetic pregnancies and 6 women who were ultimately delivered of an infant weighing less than the 5'thicentile for gestational age and sex: FetaL breathing movements were present for 69;7 t, 2.66 per cent' of the time before smoking. There was a significant reduction, in the proportion of time during which, fetal breathing movements were present within 5' minutes after the start of smoking. The reduction was proeressive: reaching a nadir of 50 = 4l3'5 per cent at 30 minutes (Table 1). Recovery was not complete until 90 minutes after the onset of smoking. The mean plasma nicotine concentration before smarkin¢, was 2.6 *: 0.6' ng./ml. By the time the next:sample was taken (90'seconds after the second cigarette was finished)~ there was a highly significant elevation ir. plasma nicotine to 15.1 * i ng./ml. The conccntration felt over the nexthour it was still above control'values 60 minutes after the end ~ of smoking (g.42' * 13' . ng:/ml.j significant correlation was observed be- tween the rise of plasma nicqtine after sntoking and the fall in the amount of fetal urcathing movements~' The mcau carboxyhem'og?oLin con- oentration in 13 womcn with normal pregnancies rose from 1.64 * 0.38'percentbeforc: smoking'to 2.74 * 0.31 per cent at' 30~minutes after the end of smoking. ln 10 women with precclampsia tQtere was no signilicant reduction imfcta'1 breathing after smok- ing (Table I'). The plasma nicotine concentration before smoking, was 1.7 t 0:5 ng./ml., similar, tw the pre-smtnking value in nbrmal patients. A, significant rise to 14 t 2.3 ng./ml. was observed 90 seconds after the secondI cigaret'te was smoked. ~ The levelithen fell progressively over the next hour. it remained significantly elevated at 60' minutes~~. TABLE 11 Fetal breathins movements in normal'and abnormal'prcgnancits before and nftersmoking tobacco cigarettes Proportion of time that fctai'breathing movementrwerrpresent (per cent) Mean * SE Time, Normal pregnancies (n - 19) Pre-eclampsia (n - 10) • Diabetesv (n - 12) Smail-ftirr dates (n - 6) Pre-smoking control 69.7 = 2.7 77.2' t 31 74.8 * 2:8 56.0 * 6.8!1' 5 minutes smoking 59 . 4'• 70i0 t 41;'5 66.5 * 5 40.2' * 1Z:4 l01minutessmoking 58'•3 _ s.6~ 63:8 t 7.24 66.0 t 5:3 34.6' ~ 12"' 15 minutcs smoking 56.6 = 5.6" 67:3' ~ 5.9 56.2 t 6' 24.6 = 111 L4's 301minutes SO _,4.351'• 71.3 6.2 :2 59.7 7.8 8 35.0t,1+42 .0 . 45 minutes 53.9 3 5.6' 73:8' t 4 70:8' t 4.5 40l0 t 8 60iminutes 59.8 = 4:6' 63:8' ~ 6.5 59:1 t 6.,1tJ'• 56.5 *, 7.7 75'minutes 54 s 5.1•' 74L7t:6',lD, 73:6t 3.5 57 * 10.4 90lminutes 64.7 = 5 • p < 0.05 as compared to control. •• p < 0.01 as compared'.to control. t p < 0.001 as compared to the norrnal' pregnancies., 100S0S2ngg .... _.~_ __...._... ., .....~ --- -_. . P v 'C-,

(_~) MANAGEMENTOF'NORMAL PREGNANCY. LABbR ANO PUERPERIUM The, pre-smoking blood' sugar levels were ! signifi- eantly greater in the preeclamptic patients.than in the normals. There was a small fall inibloo&sugar observed after smoking. - The proportion of time that fetal breathing, movements were presirnt before smoking in 12, diabetic women was 74.3 t•2.8 per cent. After smokine there was a fail imthe amount of fetal breathing which, reached statistical significance 15 and 60 minutes after the onset of smoking (Table 1'). The mean plasmanicotine before smoking. 3.2 * 0:75 ng:/ml., rose to a peak of 18.6 * 2.2 ng./ml. at 90 secondfr after smoking ended. It feff (gressively over the next hour, remaining sig- antly elevated above control values at 60 minutes. There was a significant correlation be- tween the rise of plasma nicotine after smoking, and the fall in the. amount of fetal breathing. The mean blood sugar beforesmokingwas 101.2 t 9.5 mg./dl..,signiGcantly higher than the pre-smoking levels in the normal group. There was a faU in blood sugar aftKr smoking. In fetuses subsequently identified as small-for- dates, fetal breathing movements were present, fbr 56.0* 6.8 per cent of the time before.smoking; significantly.less than the pre-smoking values in th( rma4 the diabetics and the preeclamptics: There was a progressive fall in the amount of fetal breathing within five minutes after the onset of smoking, to reach a nadirat, lS minutes. Reeovery 71'7 was complete by % minutes,(Table 1). In 31of 5 fetuses,, 10 minutes after the onset of smoking, intermittent low frequency (10 to 15 minutes) large amplitude chest wall movements appeared interspersed among normal fetat breathing move- ments. The plasma nicotine concentration rose to a peak of'17:3 * 1L8 ng./ntl: 90!seconds after the second!cigarette was smoked and then fell progres- sively overthe nezthour. It remained significantly elevated at 60 minutes. There: was a signi'ficant relationship between the change, in plasma nico- tine and! fetal breathing during, smoking. No sig- niGcant change in blood!sugar was observed after smoking. Sinoking non-nicotine (herbal)~ cigarettes pro- duced increases in carboxyhemoglobin concentra- tions similar to those observed after smoking, tobacco cigarettes, and was not associated witha fall in the incidence of fetal breathing movements. Chewinggum containingnicotine produced rises in plasma nicvtine concentration similar to those isbserved after iirnoking tobacco cigarettes andlwas associated with a significant reduction in the incidence of fetal breathing movements. Hence nicotine appeared to be the factor in cigarette smoke responsible for the reduction in the inci- dence of fetal breathing movements. Nicotine was present in the cord blood of infants whose mothers smoked. ;(1lytore scientific evidence isaccumul'ating,to prove that nicotine is harmful to the developing fetus. Apparently nicotine causes a, decrease in uteroplacental circula- tion which results in snraln-infants-fior-gestatimnal-age. The work of'Manning.and Feyerabend shows that fetal breathing is reduced soon after a mother smokes acigarette., The reduction in rate! of fetal respirations per minute a!ppears not to be related to int:raa.sed'rnaternal levels of ca~rboxyhemo} globini so com!mon in cigarette srnokets but, is caused, by nicotine in maternall and •fetal bloods. The American Academy ofPediatrics has recently sent an officesign, to all of its members~ so that each can post one in his reception, room which, reada "For the Health of Our Children, Please Don'r Smoke." Obstetricians could weili post the same sign in their officcs: The Committee on Environmental Hazards of the Academy has published an editorial in Pediatrics. 57. 411, 1976; which details the many hazards of smoking by the mother and byotherstolthe developing fetus. It is thought that maternal smoking adds~ not only to the increased incidence of small-for-gestational>agc infants but causes increased fetal wastage (Report of aV1/'HO Committee:~ Smoking and Its Effect on Health, Technicali Reports Series 568, Geneva, WHO, 11975). Second hand smoke inhaled from the smoking of others is also a hazard to health. S. Harlap and A. M. Davies found' that infants of mothers~who smoked had i

~ ,~ 718 OBSTETRICAL AND G'1"NECOLOGICAL SUFtVEY signif0cantly more admissions to the hospital for bronchitis or pneumonia diaringg the first year of life'~ than did children of non-smoking mothers (Lancet, 1: 529, 1974)l =Iga ' Last but not least, it has been shown that children of smoking parents smoke eariierand,' more frequently than children of nonsmoking, parents(IliliealtihServidcs~+t ;' and Mental Health, Administration: Teenage Smoking: National' Patterns of Cigarette Smoking, Ages 1'2-1B, in, 1968-70, Rockville, Maryland, publication (HSM) 72-7508, 11972'). It has been my expcrience that most pregnant women can be encouraged to cease ; smoking for the benefit of'their children. Obstetricians now have the scientific infiormation available to explain to patients why smoking is harmfial'tolmotheran3 ~' child and should' include this advice in prenatal care.-Ed.)