Length of pregnancy < 37 weeks in relation to NVP or HG
30. LENGTH OF PREGNANCY
1. Women experiencing vomiting were less likely to experience delivery before 37 weeks. (P=0.004). Women who vomited carried their pregnancies approximately 1.5 days longer on average before and after adjustment. (P
2. 30 hyperemesis patients mean gestational age of delivery 39.9 weeks. (36)
3. Pregnancy outcomes between hyperemesis gravidarum patients and the general population were similar in the two groups 38 weeks. The percentage of infants born before week 37 of gestation was 22% in the general population, similar to 23% in the hyperemesis group. 193 women with hyperemesis gravidarum. 13,053 pregnant women in study population. (61)
4. Babies of gravidas admitted for hyperemesis gravidarum are not at increased risk of prematurity i.e. < 37 weeks. 138 patients with HG. Mild HG = n 40, 7 delivered before 37 weeks = 17.5%. Severe HG n = 98, 11 delivered before 37 weeks = 11.2%. Controls n = 12,335, delivered before 37 weeks, 1,370 (10.7%). (62)
5. Maturity at delivery the same for patients with vomiting and those with no vomiting. No vomiting 38.9 ± 3.3 weeks. Vomiting 39.4 ± 0.8 weeks. 526 women with no vomiting, 927 women with vomiting. (63)
6. There was no statistical difference in the length of gestation between patients with hyperemesis gravidarum and the control group. Hyperemesis 164 patients 38.8 weeks. Controls 209 patients, 39.1 weeks. (64)
7. All infants of mothers with severe hyperemesis gravidarum (n=9) were 38 weeks or beyond at delivery. (73)
8. Gestational age at birth, 38.7 ± 2.7 weeks. 162 patients treated for HG over three years. (82)
9. The mean gestation at delivery in the three groups (severe HG n=46, mild HG n=26 and controls n=8,802) was not different. Controls n 8,802, 39.4 ± 1.9 weeks. Severe HG n 46, 38.9 ± 2.4 weeks. Mild HG n 26, 39.2 weeks. (28)
10. There were no significant differences in gestational age at delivery, both 39.2 + 39.5 weeks. 64 women with HG n = Group A 30, n = Group B 34. (42)
11. Patients with HG admitted to hospital once or those admitted more than once showed no difference in gestational age at delivery. Single admission n = 70 women, 38.9 ± 2 weeks. Multiple admission n = 39 women, 38.3 ± weeks. (33)
12. No correlation between nausea and pre-term labour. 855 singleton deliveries. (6)
13. NVP not related with length of gestation. 873 women in the study. 69% had NVP. (44)
14. Our observations indicate that nausea and vomiting of pregnancy does not imply an excessive risk of pre-term birth. 309 singleton pregnancies. (13)
15. Moderate increase in somewhat shorter pregnancies, 36-40 weeks, in hyperemesis gravidarum. But not for very short pregnancies (below 36 weeks). The excess for < 38 weeks gestation is statistically significant. (P
16. Pre-term birth occurred at a reduced rate after meclozine use. 16,536 women used meclozine in the first 12 weeks of pregnancy mainly for NVP. (133)
17. 17 Patients with hyperemesis gravidarum in the study. Apart from one premature delivery at 33 weeks, all patients gave birth between 38 and 41 weeks of gestation. (125)
18. Compared to women without hyperemesis n=127,835 infants born to women with hyperemesis and with low pregnancy weight gain below 7kg [15.4lb] n=144 were more likely to be born before 37 weeks. (158)
Total: One Reference
Women with HG or NVP not likely to experience delivery before 37 weeks – Total 19,646 pregnancies with 886 pregnancies with NVP or HG
(6) (18) (28) (33) (36) (42) (44) (61) (62) (63) (64) (73) (82) (13) (133) (125)
Total: Sixteen References
Moderate increase in somewhat shorter pregnancies in hyperemesis gravidarum. (29)
Total: One Reference
There is therefore no association between HG or NVP and premature labour, unless the woman with HG also has low pregnancy weight gain below 7kg (158).
Total: One reference.
Did you know?
Hyperemesis Gravidarum rarely ends at 12 weeks of pregnancy. It typically improves in the middle of pregnancy, but symptoms often last until birth.
Please note this guideline is for moderate to severe NVP symptoms rather than HG
RCOG Green-top Guideline No. 69
The Management of Nausea and Vomiting of Pregnancy and Hyperemesis Gravidarum
BMJ Clinical Update 2018
Management of severe pregnancy sickness and hyperemesis gravidarum
The risk of a baby being born with a congenital abnormality - the difference between relative and absolute risk
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