5 Pregnancy And Birth
5.1 This chapter provides a detailed description of differences in the pregnancies resulting in, and the births of, the Birth Cohort2 children according to the mother's age at the child's birth. All data presented is drawn from Birth Cohort2 mothers. Information is provided on health and health behaviours in pregnancy, including use of supplements and smoking, drinking and drug use. Details are also presented on the type of delivery, the mother's perceptions of the birth and the child's birth weight and gestation.
- Mothers aged under 20 tended to report poorer health behaviours during their pregnancy. Compared with mothers aged 25 or older, they were less likely to use supplements such as folic acid and vitamin D, more likely to smoke and, amongst those who smoked when they became pregnant, less likely to stop. They also had poorer perceptions of their general health during pregnancy.
- Mothers in their early twenties reported more positive health behaviours during their pregnancy than those aged under 20, but they remained significantly poorer than for mothers aged 25 or older.
- There were many positives too. Mothers aged under 20 were less likely to have drunk alcohol during pregnancy, more likely to have had a normal birth (without assistance or a caesarean section) and to perceive the birth as a positive experience - reporting it to be better or much better than they expected.
- In relation to lower use of folic acid prior to pregnancy and smoking, the behaviour of mothers aged under 20 was distinct from all other mothers. However, use of vitamin D, alcohol consumption and birth experience were all quite similar for mothers aged under 20 and those aged 20-24.
- There were no notable differences by maternal age in the prevalence of low birth weight, premature birth or having an illness or problem during pregnancy.
Self-reported health and illness during pregnancy
5.2 Mothers aged under 20 and those aged 20 to 24 assessed their health in pregnancy similarly and each were less likely than those aged 25 years and above to report more positive health. As shown in Table 5.1 and 5-A, 45% of mothers aged under 20 and 48% of those aged 20 to 24 years old reported that they had kept 'very well' during their pregnancy compared with 57% of mothers aged 25 or older. The proportion of those who reported that they were 'not very well' or 'not at all well', in contrast, was similar in the youngest and oldest age groups (15%/14%) and slightly higher amongst the middle age (21%).
5.3 There was no significant difference in the percentage of mothers of different ages reporting that they had a specific illness or problem during pregnancy (Table 5.2) with around two-fifths (39%) of all mothers doing so.
Vitamin supplements taken during pregnancy
5.4 Mothers were asked whether they had taken certain vitamin supplements prior to and during their pregnancy. There were stark differences in the extent to which this occurred according to age. As shown in Table 5.3, just 13% of mothers aged under 20 took folic acid supplements prior to becoming pregnant compared with 62% of mothers aged 25 years and above. Similarly, a much greater percentage of mothers aged 25 or above than younger mothers (23%) took vitamin D prior to their pregnancy (23% compared with 3% of mothers aged under 20 and 5% of those in their early twenties, Table 5.4). As both folic acid and vitamin D are recommended to improve the health and development of the baby, these large differences are likely to be explained by differences by age in the extent to which the pregnancy was planned. Pregnancies amongst older mothers are significantly more likely to be planned, meaning those mothers are more likely to take the recommended vitamin supplements. For example, data in Table 5.5 show that whereas 76% of mothers aged 25 or older said that the pregnancy was planned by her and her partner, the same was true for only 13% of mothers aged under 20.
5.5 During the first 3 months of pregnancy, use of vitamin D increased amongst mothers in all age groups and the gap in use of folic acid decreased between older and younger mothers. 81% of mothers aged under 20 took folic acid during this period compared with 96% of mothers aged 25 years and above.
5.6 Around three-quarters of mothers aged under 20 (77%) and of those aged 20 to 24 (72%) did not take vitamin D supplements at any stage of their pregnancy compared with around half (49%) of mothers aged 25 and over. 18% of mothers under 20 did not take folic acid compared with 13% of mothers in their early twenties and 3% of mothers aged 25 or older.
Alcohol during pregnancy
5.7 In the self-complete module of the questionnaire, respondents were asked how often they drank alcohol during their pregnancy. Whilst the majority of all mothers claimed that they never drank during pregnancy, mothers aged 25 or older were more likely to have drank, and to have done so more frequently than were mothers aged under 20 and those aged 20 to 24. 90% of mothers in each of the younger groups said they had drank no alcohol during their pregnancy compared with 77% in the older groups (Table 5.6).
5.8 18% of mothers aged 25 and older drank less than once a month and 4% drank 2-3 times a month compared with around 9% and 1% respectively of mothers in the two younger groups. Differences in the frequency and quantity of current alcohol consumption by age group are discussed in section 6.
Smoking during pregnancy
5.9 The self-complete section of the questionnaire also contained questions about whether the mother smoked cigarettes during her pregnancy. The figures in Table 5.7 reveal a strong relationship between maternal age and smoking habits. Mothers aged under twenty were significantly more likely than older mothers to have smoked during their pregnancy and, amongst those who smoked prior to their pregnancy, were less likely to reduce or stop their smoking.
5.10 As shown in Figure 5-B, 54% of mothers aged under 20 smoked to some extent during pregnancy compared with 43% of mothers in their early twenties and 16% of mothers aged 25 or older age. Mothers in their early twenties are much more similar to those aged under 20 on this measure than they are to those aged 25 or older.
5.11 Amongst those who had smoked during their pregnancy (Table 5.8), once they found out that they were pregnant, 50% of mothers aged 25 or older stopped smoking compared with 37% of mothers aged under 20 and 36% of those in their early twenties. 15% of mothers aged under 20 who smoked when they became pregnant continued to do so during their pregnancy compared with 8% of mothers aged 25 or older who smoked.
Drugs during pregnancy
5.12 Around one quarter of mothers said they had taken illegal drugs at some point in their lives. Of those who had reported ever taking illegal drugs, the majority across all age groups had not taken any during pregnancy. As shown in Table 5.9, 97% of mothers aged under 20, 94% of those aged 20 to 24 and 96% of those aged 25 had either given up taking drugs a long time before becoming pregnant, when trying to become pregnant or did not take any drugs during pregnancy.
Type of delivery
5.13 The data in Figure 5-C show clear differences in the method of delivery across the maternal age groups indicating that older mothers were more likely to have complications. The majority of mothers aged under 20 (72%) and those aged 20 to 24 (57%) had a normal delivery. In contrast, less than half of those in the older group did the same (44%). 33% of mothers aged 25 and over had a caesarean section - including 22% after labour began ('emergency' sections) - compared with 14% of mothers aged under 20 and 24% of those in their early twenties. Forceps or Ventouse (or both) were also more likely to have been used for older mothers (23% compared with 18% of those aged 20 to 24 and 13% of mothers aged under 20).
5.14 Differences in the type of delivery by age are, perhaps, also reflected in the mother's expectations for and assessment of the birth (Table 5.11). For example, just over half of mothers aged under 20 (52%), the group most likely to have a normal delivery method, said that giving birth was either much better or better than they expected compared with 35% of those aged 25 or older. 30% of mothers aged 25 years and over said that the birth was worse than they expected, compared with 22% of mothers aged under 20.
5.15 Mothers were also asked who was present at the child's birth. The majority of mothers in all age groups said the baby's father had been present at the birth (Table 5.12). However, this was more common amongst older mothers. 93% of those aged 25 or older said the baby's father had been present, compared with 71% of mothers aged under 20. Most mothers aged under 20 (57%) also said their own mother or mother in law was present whilst just one in ten (11%) mothers aged 25 and above said the same.
5.16 No significant differences were found in children's average birth weight according to the mother's age group. There was, however, a small difference between teenage and older mothers in the percentage of babies with low birth weights, as shown in Table 5.13. 5% of children with mothers aged under 20 had a low birth weight compared with 8% of those whose mothers were aged 25 and above. This weight has not been adjusted for gestational age though mothers aged under 20 were more likely to say the baby arrived late (usually related to a heavier birth weight) compared with mothers aged 25 or over who, in contrast, were more likely report giving birth early or on time (Table 5.14).
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