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Abstract The management of labour ls basic to the practice of obstetrtcs, Although most patients have a normal spontaneous labour at term. On occaslon. The natural course of parturition must be modified. Preventing or arreIJtlng Idiopathic preterm labour may be required or conversely initiating and maintaining labour may be needed. Induction of labour represents one of tile two m.ost potent weapons l’n the hands of the obstetrtclan In influencing the , course and success of pregnancy. the other being cesarean section, These are the ob”stdTIclan’s methods of terminatlng pregnancy at O! near term. As the effectiveness and rellablllty of labour-inducing methods increased. there was also a parallel increase In the acce.ptablllty of the obstemclane to apply these methods. Many factors are Involved In the control of the onset and progress of human parturition offering. at: least theoretically. a wide army of potentia] approaches to controtllng labour In ctlnlcai practice. 0.t It is almost true [hat the cioser the patient to the onset of labour, the easier and more successful the Induction will (Calder 198.3) The best guide to this progress Is an assessment of the state of the cervix using scoring system such as that described by Bishop (1964). In practical terms, patients WIth unripe cervix l.e, low BIshop score, need more preparation before labour, l.e, the method employee for ~nductlon should be capable of reproduelng events of pre I~bor, This can be achieved by employing a cervical ripening agent, before Induction of 1abour.(Noah, et aJ 19871” Although the former Is never pertermed without Intentlon of proceeding to the latter, It Is useful for clinical purpose to distinguish between them. (:Noah et al 1987) The clinical purpose of Ind.uction of labour has al!ways been to Improve the outcome when It Is perceived that allowing the pregnancy to continue In Its natural course would present some jeopardy to the mother, her ba:l:JyOr to both. It has alWl’\YS reaw”~ Intervention of this sort may In Itself carry 118ks.and e:... sui rlskshave to be considered in • an overall assessment In the management of the Individual case. The risk ·of Induction should never be allowed to exceed the dangers of allowing the pregnancy to continue. Justiflcation ofinductioD (.•••eo to deliver): The guiding prmctpte when consIdering labour Induction should be to appi)’ t.oevery pregnancy (the obstetric balance) (Calder 1983)” For the great maJority of pregnancies. the balance will remain securely tipped agablst intervention! The rLs~ of Interruption will outweIgh those of non lnterventlon and these conditions will.continue to prevaJ:1until the spontaneous onset of labour at term results In the delivery of a healthy offspring. In a mJnortty of pregnancies, however. the risks inherent in oontlnulng the pregnancy may be perceived to rise to a point where the ballance tips in favour ’of Intervention. Only then can Inductlon be justifiably consIdered {Calder. 199 I) Pactors affi:ditlgtbe course 01 induOf!d. labom I. Uterinesensitivity As pregnancy proceeds. the uterine muscles become more. and more. !mtable and pregnant women fe~ more and more weeks of pre;gnancy. At the ” 4. same time, the sensitivIty of the uterine muscle to oxytocin Is increased (Anderson, et al 1969), and this sensitlvlty to oxytocin can also be related to the degree of ripeness of uie cervix. 2. CenlcaI ripenbtg: During the last weeks prior to labour, the cervix undergoes btochemicar as well as structusal chang~ that can be detected dlnlcally(t1endrlcks, et a! 1970). TheBe are referred to as cervtcal ripening and the degree of this ripen1l:lg at the Ilme of active labour Is of a decisive Importance with regards Its course and duralion. These changes are manifest as softening.. shortening and dHataUon of the cervix. Various scores, (Calder. 1983}have; been proposed for the quantltative assessment of cervlcal rlpeness. I5lshop score Is the most commonly used one In our country. This system ~ses a scale (rom 0-13 to assess the station of the presenttnq fetal part, and the cervical length, dilatation, consIstency and position in the birth canal. Also the modlfled Bishop score Is another method of assessmelll(Bishop, 1964). 3. Farity: Primiparae have a longer duration of labour than multiparae ill both the first and the second stages of labour. Measured in Bishop score units the difference In duration of 5.• labour between prtrnt and nulliparae Is 3-4 points (Bishop. 19M}. It does not appear. however. to be mare difficult to Induce labour in primiparae. provided of-oourse that the cervtx is ripe (BishOP, 1964). Un~ortunately, the cervix Is more often unripe than in ml.l!llllparae. 4. other factoJ’sl It ~ unclear whether the ase of the mother has any influence on the course of labour .(Noah. et at 198?} However, It Is recognized that the cervIcal condition In elderly primiparae Is more often unnpe than In younger primiparae. NeIther the size nor the gestatIonal age of the foetus seems to have a direct Innuence on either the duration or Induc:1btllty of labour .(Lange, 1982) .J. ’ro” |