Table 3.
Oxytocin levels in blood samples collected during physiological birth in the 20 selected papers. Values from pregnant and non-pregnant women are included. All values are presented in pg/mL, with SD or range in parentheses
| First author, year | Labour and birth (pg/mL) | Time for blood sample | Pregnancy (pg/mL) | Gestational week (w) | Non-pregnant (pg/mL) |
|---|---|---|---|---|---|
| Coch 1965 [13]a | 167 | Active labour | |||
| Kumaresan 1974 [14]a | 302 (58.3–725.0) | Active labour | 110 | 4 w | < 1.7 |
| 275 | 40 w | ||||
| Kumaresan 1975 [15]a | 150.0 (18.3) | 10 min before birth | |||
| 136.7 (20.0) | Immediately after birth | ||||
| Gibbens 1976 [16]a | 4.2–20.8 | 1st – 3rd stage | |||
| Vasicka 1978 [17]a | 73.3–273.3 | Active labour | 211.5 (35.2) | 24 w | |
| 255.0 (44.3) | 40 w | ||||
| Dawood 1979 [18] | 0–86 | 1st stage of labour | 17.9 (2.1) | 1–20 w | |
| 28.9 (4.7) | 21–30 w | ||||
| 32.9 (2.9) | 31–32 w | ||||
| 26.4 (4.8) | 38 w | ||||
| 74.2 (14.2) | 39 w | ||||
| Leake 1981 [19]a | 2.2 (0.3 | Latent phase | 2.2 (0.2) | 15–42 w | 2.3 (0.3) |
| 2.7 (0.3) | Active labour | ||||
| 1.8 (0.2) | Visible head | ||||
| 7.0 (1.8) | Delivery of head | ||||
| Otsuki 1983 [20]a | 21.0 (63.3–146.7) | Active labour | 8.3 | 20 w | |
| 20.8 (12.8) | 36–41 w | ||||
| Goodfellow 1983 [21] | 7.2–46.0; | Full dilatation | |||
| 8.8–85.0c | Crowning of head | ||||
| Husslein 1983 [22] |
50.7 (10.7) 29.1 (9.7) |
Full dilatation 30 min postpartum |
|||
| Fuchs 1983 [23] |
45 (3.9) 21.1 (6.4) 49.1 (10.9) 58.8 (9.9) 110 (22.7) |
1st stage 1–3 mU/min SOT inf 4–6 mU/min SOT inf 7–9 mU/min SOT inf 10–15 mU/min SOT inf |
15.4 (8.7) 17.4 (4.8) 19.9 (3.1) |
1–2 weeks before labour Before induction At term |
|
| Amico 1984 [24]a | 1.7 (0.5) | Arrest in active labour | |||
| Takeda 1985 [25]a | 32.8 (5.5) | Active labour | 26.8 (4.8) | 7–41 w | 8.0 (0.8) |
| Takagi 1985 [26]a | 75.3 (32.7) | Before emergency CS | 11.7 (8.8) | ||
| De Geest 1985 [27]a | 276.7 | < 3 cm cx dilatation | 78.3 | 8–12 w | |
| 298.3 | 5–7 cm | 128.3 | 20–24 w | ||
| 281.7 | 10 cm | 208.3 | 30–34 w | ||
| 276.7 | 2nd stage | 226.7 | 38–42 w | ||
| Kuwabara 1987 [28]a | 51.0 (8.3) | Immediately after birth | 27–28 | 6–41 w | 6.8 (0.8) |
| 33.3 | At term | ||||
| Thornton 1988 [29]b | 3.2 (2) | Crowning of head | |||
| 6.4 (2) | After delivery of shoulder | ||||
| 11.6 | Mean peak after birth | ||||
| Oosterbaan 1989 [30] |
65 (9) 12 (9) |
Immediately after birth During prelabour CS |
|||
| Fuchs 1991 [31]a | 1.8 (0.2) | 1st stage < 6 cm | 1.5 (0.5) | At term before elective CS | |
| 2.3 (0.6) | 2nd and 3rd stage | ||||
| Stoche 2001 [32] | 7.4 (2.1) | 1st stage | |||
| 6.6 (3.1) | Before analgesia |
pg/mL picograms per millilitre, mU/min milliunits per minute, SOT inf synthetic oxytocin infusion, CS caesarean section, μU/mL microunits per millilitre, pmol/L picomoles per litre
aOxytocin levels have been converted from μU/mL to pg/mL
bOxytocin levels have been converted from pmol/L (pM) to pg/mL
cCorrected from Table 1 in Goodfellow 1983