Biol. Neonate 26: 159-173 (1975)
Some Physical and Biochemical Parameters during Normal Labour Fetal and Maternal Study
G eorges P o n t o n n ie r . F rancis P u e c ii , H élène G randjea n an d M ichel R o lla n d Clinique Obstétricale de l'Hôpital de La Grave, Toulouse
Key Words. Normal labour • Monitoring • Acid-base equilibrium ■Blood sugar Abstract. A statistical study of parameters of uterine contraction, fetal heart rate, acid-base balance and glycaemia has been made in 30 patients during spontaneous and clinically normal labour for each 2 cm of cervical dilatation. The study of uterine contrac tility gives the mean values and 95% limits of parameters of uterine contraction as labour progresses. The fetal heart rate is stable during dilation, on the other hand, during the expulsive phase, alterations of fetal heart rate appear, modifications which give evidence of trial that expulsive phase is for the fetus. The study of fetal and maternal acid-base balance shows little change during cervical dilatation, changes towards acidosis during expulsive phase, as importance of fcto-maternal relationships. These relationships meet again on the study of glycaemia.
Very many papers have been written these last 10 years on the study of physical and biochemical parameters during labour, very many on fetal distress, much less on normal labour. That is the reason why we have tried in this study to gather the maximum of quantitative data on the uterine dynamic, the fetal heart rate and the fetal and maternal acid-base balance status and glycaemia. So as to be able to constitute a complete document of the clinically normal labour. The information that we have collected have been subjected to a statistical analysis. The presentation of the results and the comparisons that we have made on these have been done according to dilatation.
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Introduction
160
Pontonnier/P uech/G randjean/R oli-And
Material This investigation involved 30 deliveries defined as 'normal' following clinical criteria. These criteria were as follows: normal pregnancy; spontaneous onset of labour between the 38th and 42nd weeks of pregnancy in vertex position; clear amniotic fluid; clinically normal uterine dynamics; normal basal fetal cardiac rhythm on auscultation; no drug administration; at birth, newborn weighing 2,500 g or over, with Apgar score greater than or equal to 8/10 at the 1st and 5th min. The other characteristics of the thus selected cases were as follows: parity, 24 primiparae, 6 multiparae; mean age maternal primiparae 22.5 years, multiparae 25 years; orientation, LOA in 23 cases, ROP in 6 cases, LOP in I case; mean weight of newborns, 3,310 g; Apgar score, 10/10 at the 1st and 5th min in all 30 cases; initial dilation on starting monitoring. 3 cm in 15 cases, 4 cm in 13 cases, 6 cm in 2 cases: recording of expulse stage, performed in 19 cases; mean duration of dilation on monitoring, 3 h 45 min in primiparae, I h 50 min in multiparae: mean duration of expulsion, 30 min in primiparae, 10 min in multiparae.
Intraamniotic pressure and instantaneous fetal heart rate were recorded continuously with Dassault fetal monitoring apparatus (Roche-Bicelectronique). Acid-base balance was assessed with II. Meter 213 apparatus, that enables to measure directly pH, Po_. and Pco». Base deficit was determined from Thew's nomogram. In 11 deliveries, we measured glycaemia with a Beckman BGA apparatus. Eight parameters were measured from intraamniotic pressure curves: tonus in mm Hg; total intensity of uterine contractions in mm Hg: true intensity = total intensity minus tonus in mm Hg: duration of uterine contractions in seconds: approximated surface area of uterine contraction. This parameter was obtained by assimilating the uterine contraction to an isosceles triangle whose base is represented by the duration of uterine contraction and altitude by its intensity, calculated as follows: intensity of uterine contraction = total intensity - (preceding tone + following tone) x | ¡2. The surface area then is obtained by the formula: surface area = duration (secs) x intensity of uterine contraction (mm Hg) x 1/2: frequency of uterine contractions, that is obtained by dividing each value for a period into 600. and the result is expressed as a number of contractions, 10 min; uterine activity I in Montevideo units (MU), the product of true intensity into frequency of uterine contrac tions/10 min [ K r a po h l et at., 1970]; uterine activity 2, the product of surface area into frequency that we shall express in Toulouse units (TU) for the sake of convenience. On heart rale curves we studied basal heart rate as beats/min, various types of baseline oscillations, classified according to H a m m ach er ' s [1968] nomenclature: type I dip and type 2 dip. We measured their lag-time, duration, amplitude, surface area, and the per centage of uterine contractions giving rise to dips. The study of biochemical parameters was performed on blood samples taken from the scalp in fetuses and from the fingertips in mothers. Feto-malernal differences were calculated only when samples were taken within 5 min of one another. We applied S a u n g ’s [1964] technique with induction of local vasodilation with ethyl chloride.
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Methods
Some Physical and Biochemical Parameters during Normal Labour
161
The presentation of results and their interpretation require the calculation of the average values of the various parameters considered, then comparisons are made between these average values in terms of the various groups defined. The groups are defined in terms of dilation. Each group corresponds to a dilation interval of 2 cm, except for the first one, for which the interval is 1 cm.
Results Uterine Dynamics We calculated the values of the parameters of uterine dynamics following two methods. The first one, that calculates the overall average for each interval from the 30 average values obtained for each delivery, enables one to study the course of the parameters during labour; the second one that calculates the average of each parameter in each interval from the whole of uterine contractions, enables to define the average values of the parameters of normal delivery and their 95% limits (2 SD on either side of the average). Course o f the parameters during labour. This investigation demonstrated that all parameters, except for the duration of uterine contractions, increase in a statistically significant fashion between the 3-4 and 8-10 cm intervals of dilatation (p
Some Physical and Biochemical Parameters during Normal Labour Fetal and Maternal Study
G eorges P o n t o n n ie r . F rancis P u e c ii , H élène G randjea n an d M ichel R o lla n d Clinique Obstétricale de l'Hôpital de La Grave, Toulouse
Key Words. Normal labour • Monitoring • Acid-base equilibrium ■Blood sugar Abstract. A statistical study of parameters of uterine contraction, fetal heart rate, acid-base balance and glycaemia has been made in 30 patients during spontaneous and clinically normal labour for each 2 cm of cervical dilatation. The study of uterine contrac tility gives the mean values and 95% limits of parameters of uterine contraction as labour progresses. The fetal heart rate is stable during dilation, on the other hand, during the expulsive phase, alterations of fetal heart rate appear, modifications which give evidence of trial that expulsive phase is for the fetus. The study of fetal and maternal acid-base balance shows little change during cervical dilatation, changes towards acidosis during expulsive phase, as importance of fcto-maternal relationships. These relationships meet again on the study of glycaemia.
Very many papers have been written these last 10 years on the study of physical and biochemical parameters during labour, very many on fetal distress, much less on normal labour. That is the reason why we have tried in this study to gather the maximum of quantitative data on the uterine dynamic, the fetal heart rate and the fetal and maternal acid-base balance status and glycaemia. So as to be able to constitute a complete document of the clinically normal labour. The information that we have collected have been subjected to a statistical analysis. The presentation of the results and the comparisons that we have made on these have been done according to dilatation.
Downloaded by: University of New England 132.174.255.223 - 1/10/2019 10:23:18 PM
Introduction
160
Pontonnier/P uech/G randjean/R oli-And
Material This investigation involved 30 deliveries defined as 'normal' following clinical criteria. These criteria were as follows: normal pregnancy; spontaneous onset of labour between the 38th and 42nd weeks of pregnancy in vertex position; clear amniotic fluid; clinically normal uterine dynamics; normal basal fetal cardiac rhythm on auscultation; no drug administration; at birth, newborn weighing 2,500 g or over, with Apgar score greater than or equal to 8/10 at the 1st and 5th min. The other characteristics of the thus selected cases were as follows: parity, 24 primiparae, 6 multiparae; mean age maternal primiparae 22.5 years, multiparae 25 years; orientation, LOA in 23 cases, ROP in 6 cases, LOP in I case; mean weight of newborns, 3,310 g; Apgar score, 10/10 at the 1st and 5th min in all 30 cases; initial dilation on starting monitoring. 3 cm in 15 cases, 4 cm in 13 cases, 6 cm in 2 cases: recording of expulse stage, performed in 19 cases; mean duration of dilation on monitoring, 3 h 45 min in primiparae, I h 50 min in multiparae: mean duration of expulsion, 30 min in primiparae, 10 min in multiparae.
Intraamniotic pressure and instantaneous fetal heart rate were recorded continuously with Dassault fetal monitoring apparatus (Roche-Bicelectronique). Acid-base balance was assessed with II. Meter 213 apparatus, that enables to measure directly pH, Po_. and Pco». Base deficit was determined from Thew's nomogram. In 11 deliveries, we measured glycaemia with a Beckman BGA apparatus. Eight parameters were measured from intraamniotic pressure curves: tonus in mm Hg; total intensity of uterine contractions in mm Hg: true intensity = total intensity minus tonus in mm Hg: duration of uterine contractions in seconds: approximated surface area of uterine contraction. This parameter was obtained by assimilating the uterine contraction to an isosceles triangle whose base is represented by the duration of uterine contraction and altitude by its intensity, calculated as follows: intensity of uterine contraction = total intensity - (preceding tone + following tone) x | ¡2. The surface area then is obtained by the formula: surface area = duration (secs) x intensity of uterine contraction (mm Hg) x 1/2: frequency of uterine contractions, that is obtained by dividing each value for a period into 600. and the result is expressed as a number of contractions, 10 min; uterine activity I in Montevideo units (MU), the product of true intensity into frequency of uterine contrac tions/10 min [ K r a po h l et at., 1970]; uterine activity 2, the product of surface area into frequency that we shall express in Toulouse units (TU) for the sake of convenience. On heart rale curves we studied basal heart rate as beats/min, various types of baseline oscillations, classified according to H a m m ach er ' s [1968] nomenclature: type I dip and type 2 dip. We measured their lag-time, duration, amplitude, surface area, and the per centage of uterine contractions giving rise to dips. The study of biochemical parameters was performed on blood samples taken from the scalp in fetuses and from the fingertips in mothers. Feto-malernal differences were calculated only when samples were taken within 5 min of one another. We applied S a u n g ’s [1964] technique with induction of local vasodilation with ethyl chloride.
Downloaded by: University of New England 132.174.255.223 - 1/10/2019 10:23:18 PM
Methods
Some Physical and Biochemical Parameters during Normal Labour
161
The presentation of results and their interpretation require the calculation of the average values of the various parameters considered, then comparisons are made between these average values in terms of the various groups defined. The groups are defined in terms of dilation. Each group corresponds to a dilation interval of 2 cm, except for the first one, for which the interval is 1 cm.
Results Uterine Dynamics We calculated the values of the parameters of uterine dynamics following two methods. The first one, that calculates the overall average for each interval from the 30 average values obtained for each delivery, enables one to study the course of the parameters during labour; the second one that calculates the average of each parameter in each interval from the whole of uterine contractions, enables to define the average values of the parameters of normal delivery and their 95% limits (2 SD on either side of the average). Course o f the parameters during labour. This investigation demonstrated that all parameters, except for the duration of uterine contractions, increase in a statistically significant fashion between the 3-4 and 8-10 cm intervals of dilatation (p
