Table 4.
Maternal synthetic oxytocin administration: newborn cord blood and maternal plasma oxytocin levels
| Publication details | Number of participants Indication Dose regimen |
Timing of maternal sampling | Maternal plasma (if sampled) and newborn cord umbilical artery (UA*) and umbilical vein (UV*) oxytocin levels, mean ± SEM, pg/mL (in original units) | Oxytocin assay Comments Important findings Other reported data |
||
|---|---|---|---|---|---|---|
| Maternal | UA | UV | ||||
| Maternal intrapartum synthetic oxytocin infusion | ||||||
|
Dawood et.al. (1978) Fetal contribution to oxytocin in human labor |
7 women & newborns Labour induction with SOT Dose regimen: Buccal and/or IV infusion Max. total dose 0.8-400 IU |
No maternal samples | (Not sampled) | 24.6 ± 9 | 69.9 ± 18.6 |
Assay: RIA Comments: Buccal SOT gives low maternal absorption Important findings: UA < UV oxytocin in SOT-exposed newborns (p < 0.01) (usually UA > UV, see studies below) Other reported data: Oxytocin levels in newborn UA and UV following pre-labour and in-labour caesarean (This data to be reviewed in subsequent systematic reviewb) |
|
26 women & newborns No SOT |
(Not sampled) | 116 ± 17.2 | 38 ± 5.6 | |||
|
Otsuki et. al. (1983) Feto-maternal plasma oxytocin levels in normal and anencephalic pregnancies |
5 women & newborns Labour induction with SOT Dose regimen: Not stated |
During 2nd stage |
63.1 ± 12.9 pg/mL (37.8 ± 7.7 μU/mL) |
25.8 ± 4. (15.2 ± 2.5) |
22.2 ± 5.5 (13.3 ± 3.3) |
Assay: RIA Important findings: No significant differences in UA or UV oxytocin for newborns of SOT-exposed vs unexposed mothers Other reported data: Significantly higher oxytocin in women with vs without SOT (p < 0.001) No significant difference in 2nd stage oxytocin in women with anencephalic vs unaffected fetus (no SOT in either group) Oxytocin levels in newborn UA and UV following pre-labour caesarean (This data to be reviewed in subsequent systematic reviewa) |
|
6 women & newborns No SOT |
29.4 ± 6.0 (17.6 ± 3.6) | 30.4 ± 8.2 (18.2 ± 4.9) | 20.4 ± 3.8 (12.2 ± 2.3) | |||
|
4 women & newborns No SOT Anencephalic babies |
22.4 ± 13.4 (13.4 ± 8.0) | (Not detectable) | (Not detectable) | |||
|
Padayachi et. al. (1988) Serial oxytocin levels in amniotic fluid and maternal plasma during normal and induced labour |
8 women & newborns Labour induction with SOT Dose regimen: 2–32 mU/min |
Collected over 4 min at 8–10 cm |
10.1 ± 1.3 pg/mL (6.07 ± 0.8 μU/mL) |
67 (40) | 37 (21) |
Assay: RIA Comments: UA and UV oxytocin estimated from Fig. 3 All induced women also had ROM Important findings: No significant differences in UA or UV oxytocin for SOT-exposed vs unexposed newborns Other reported data: Oxytocin levels in amniotic fluid (AF): No significant difference in AF oxytocin in SOT-exposed vs unexposed in early or late labour Oxytocin levels in newborn UA and UV following prostaglandin-induced labour and pre-labour caesarean (This data to be reviewed in subsequent systematic reviewb) |
|
13 women & newborns No SOT |
9.1 ± 1.2 (5.48 ± 0.6) | 30 (18) | 17 (10) | |||
|
Patient et. al. (1999) The effect of labour and maternal oxytocin infusion on fetal plasma oxytocin concentration |
10 women & newborns SOT infusion Dose regimen: 2–28 mU/min, mean 10 mU/min |
No maternal samples | (Not sampled) |
17.7 pg/mL (95% CIs: 9.7–32.1) |
7.3 (4.6–11.8) |
Assay: RIA Comments: pmol/L equivalent to pg/mL Important findings: UA > UV all groups (p < 0.01) No significant differences in UA or UV oxytocin or UA:UV ratio for newborns of SOT-exposed vs unexposed mothers Other reported data: Oxytocin levels in newborn UA and UV following maternal pethidine in labour, pre-labour and in-labour caesarean (This data to be reviewed in subsequent systematic reviewb) |
|
15 women & newborns No SOT |
(Not sampled) | 14.8 (8.7–25.1) | 7.8 (4.7–13.1) | |||
|
Pochard & Lutz-Bucher (1986) Vasopressin and oxytocin levels in human neonates. Relationships with the evolution of labour and beta-endorphins |
6 women & newborns Labour induction or augmentation with ‘oxytocic drugs’ (presume SOT) Dose regimen: Not stated |
At time of birth | 3 pg/mL | 36 | 13 |
Assay: RIA Comments: All oxytocin levels estimated from Fig. 1 Important findings: UA oxytocin correlated with UV levels (p < 0.01) UA > UV levels (p < 0.0001) and UV > maternal levels (p < 0.0002) No significant difference in UA or UV oxytocin for newborns of SOT-exposed vs unexposed mothers or following fetal distress Other reported data: Oxytocin levels in newborn UA and UV following pre-labour caesarean (This data to be reviewed in subsequent systematic reviewb) Newborn AVP levels: UA > UV (p < 0.001) and UV > maternal (p < 0.0001) all groups |
|
21 women & newborns No SOT |
2 | 18 | 8 | |||
|
10 women & newborns Following fetal distress in labour |
4 | 22 | 7 | |||
| Maternal postpartum synthetic oxytocin | ||||||
|
Sellers et. al. (1981a) Is oxytocin involved in parturition? |
9 women & newborns Postpartum SOT (No SOT in labour) Dose regimen: Combination of SOT 5 IU and ergometrine 500 μg Given IM with birth of anterior shoulder |
No postpartum maternal samples | (Not sampled) | 75 | 35 |
Assay: RIA Comments: UA and UV levels estimated from Fig. 2 Timing of cord clamping not stated Important findings: No significant difference in UA or UV oxytocin for newborns of SOT-exposed vs unexposed mothers Oxytocin levels in UA > UV (p < 0.05) in controls Other reported data: Oxytocin levels in newborn UA and UV following pre-labour caesarean (This data to be reviewed in subsequent systematic reviewb) |
|
8 women & newborns No postpartum SOT/ergometrine |
(Not sampled) | 115 | 50 | |||
Units: IU international units, mU milliUnits, μU microunits, mg milligrams, μg or mcg micrograms, ng nanograms, pg picograms, pmol picomols, mL millilitres
Oxytocin conversions: 1 IU = 1000 mU; 1 mU = 1000 μU; 1 mg = 1000 μg; 1 μg = 1000 ng; 1 ng = 1000 pg; 1 IU = 1.67 μg; 1 mU = 1.67 ng; 1 μU = 1.67 pg; 1 μg = 0.6 IU; 1 ng = 0.60 mU; 1 pg/mL = 1 pmol/L = 1pM
Abbreviations: AF amniotic fluid, approx approximately, AVP arginine vasopressin, CI confidence intervals, cm. centimetres of cervical dilatation, fig. Figure, IM intramuscular, IV intravenous, MCR metabolic clearance rate, min minutes, RIA radioimmunoassay, ROM rupture of membranes, SE standard error, SEM standard error of the mean, SOT synthetic oxytocin, UA umbilical artery, UV umbilical vein, vs versus
aUA and UV: UA carries blood from fetus to placenta, UV carries blood from placenta back to fetus
bFurther systematic reviews (manuscripts in preparation) will report maternal and newborn plasma oxytocin levels in relation to caesarean section, epidural analgesia, opioid analgesics and other interventions