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Older mothers

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

Women in developed countries are delaying their first pregnancy, significantly. Over the past three decades, the mean maternal age at the birth of a woman’s first child has increased in the USA from 21 to 25 years and in Japan from 26 to 28 years.

Also significant is the number of women embarking on pregnancies over the age of 45 years. These are mostly assisted reproduction pregnancies with in vitro fertilisation using donated ova where the woman is aged more than 50 years. Women contemplating motherhood at this age need to know the risks involved so the data of Simchen et al. from Israel are of interest (Obstet Gynecol 2006;109:1084–8).

The study group of pregnancies in women aged 45–64 years had a mean gestational age of 37.6 weeks with a mean birthweight of 2685 g, with a multifetal rate of 23%. Preterm delivery rates were very high. Complication rates of diabetes, hypertension, hospitalisation and caesarean sections were high, all of which increased with maternal age. Despite these difficulties, the outcomes were generally satisfactory compared with those delivering at 30 years of age.

The authors describe their results as ‘somewhat disturbing’ and make no comment on the costs—financial, resource and societal—of such pregnancies. They leave us to dwell upon the moral and ethical issues.

Amniocentesis and pregnancy loss

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

The standard risk quoted for pregnancy loss after a midtrimester amniocentesis is 1 in 200. This figure is largely historical, and the First and Second Trimester Evaluation of Risk for Aneuploidy trial (FASTER) now allows revision of the statistics (Eddleman et al., Obstet Gynecol 2006;108:1067–72).

The FASTER Consortium in the USA looked at 35 000 pregnancies between 10 and 14 weeks of gestation that were being followed for Down syndrome evaluation. About 32 000 did not have an amniocentesis, the control group, and they had a miscarriage rate of 0.94% before 24 weeks of gestation. About 3000 did have a genetic amniocentesis, and they had a miscarriage rate of 1%, making the difference of 0.06% which translates into a risk of 1 in 1600. The trial was conducted in 15 clinical centres throughout the USA, without prescribed needle size, and the procedure was carried out by clinicians with varied experience. It reflects the current situation, rather than research circumstances, which improves the generalisability of the results for quoting in routine practice.

A sensible approach to Down syndrome screening is described by Rozenberg et al. (Am J Obstet Gynecol 2006;195:1379–87) who surveyed an unselected French population of 15 000 women. They performed routine maternal serum marker tests in the first trimester and reacted to positive values. At the 20-week ultrasound scan, structural features were sought that are associated with Down syndrome, thus providing a follow-up safety net while checking the fetus for nonchromosomal abnormalities. Detection and screen-positive rates were 90% and 4%, respectively, using this combination method, which seem highly acceptable.

New contraceptive use

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

Currently, the most commonly used emergency contraception products are progesterone-only based. Seventy-five milligrams of levonorgestrel in two doses 12 hours apart or 150 mg as a single dose is the standard preparation against which other newer agents are being tested. The latest contender is a progesterone receptor modulator, a generation on from mifepristone which blocks progestational activity. The drug is called CDS-2914 (Creinin et al., Obstet Gynecol 2006;108:1089–97).

In a head-to-head trial against levonorgestrel, the new drug was more effective, preventing 85% of pregnancies compared with 70%, but this difference was not significant. Adverse effects of nausea and delay in the next menstrual period were similar so the authors conclude that yet another drug is effective in the prevention of pregnancy postcoitally.

Oral contraceptives taken in the standard fashion can somewhat relieve premenstrual symptoms and/or the premenstrual dysphoric disorder. However, the hormone-free days of the placebo tablets allow endogenous estrogen production, which is associated with disquieting effects.

Certain progestins have more beneficial effects on the premenstrual syndrome than others, with drosperinone being proven effective in clinical trials, probably because of its derivation from spironolactone and its antimineralocorticoid activity. Coffee et al. (Am J Obstet Gynecol 2006;195:1311–19) therefore tried the oral contraceptive combination of drosperinone and ethinyl estradiol (Yasmin; Berlex Labs) for a 21-day cycle, then a 6-month continuous regimen to test its suppression of premenstrual symptoms.

The 21 days on and 7 days off cycles did help, but the 24-week continuous pattern was associated with a marked and statistically significant reduction of symptoms. Ninety-two percent of the participants completed the trial, and with extended oral contraceptive regimens gaining popularity, it seems that women suffering from premenstrual symptoms or dysphoric disorder can be offered definitive treatment.

Twins and intelligence

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

During the 20th century, it was firmly believed that twins had lower mean intelligence quotient (IQ) scores than singletons. Twins born preterm had consistently poorer cognitive performances when measured up to the age of 10 years, and this was attributed to both prematurity and growth restriction.

It appears that these data will need updating, according to Danish twins tests of teenagers by Christensen et al. (BMJ 2006;333:1095–7). The babies were born in the late 1980s, and compared with singletons, the twins had no cognitive disadvantage, scoring weight for weight the same on IQ scales. There was a change in IQ with birthweight, which was measurable, but small, about 0.1 standard deviations per kilogram. So it seems better obstetrics, neonatal care, nutrition or delayed testing until adolescence evens out the educational performance between twins and singletons in the 21st century.

Breastfeeding and intelligence

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

There are many advantages of breastfeeding to the mother and baby. These include the effect of colostrum on immunity, fewer diarrhoeal diseases, the benefits of omega 3 fatty acids on visual developments in small infants, and improved bonding and less breast disease later. It remains unclear whether the child’s intelligence is affected by breastfeeding, although it remains an unequalled way of providing ideal nutrition.

To look at the effect of breastfeeding on intelligence, Der et al. defined the known variables in more than 5000 children and teased out factors such as education, race, wealth, smoking, birth order, birthweight and home environment (BMJ 2006;333:945–8). In general, breastfed babies scored four points higher in testing than formula-fed infants, but almost all this effect was attributable to the mother’s IQ. In other words, inheriting the mother’s cognitive abilities was more important than being fed her breast milk as measured by intelligence tests. These findings can be used to reassure mothers who cannot breast feed but in no way detract from the many other plus factors which should persuade women to breast feed, if possible for at least 6 months.

When to clamp the cord

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

It appears that the practice of early cord clamping is about to change. Traditionally, midwives and doctors clamp the cord immediately after delivery and pass the baby off as soon as possible, but there is little evidence that this unnatural practice has any benefit to the baby. All studies from developing countries show that infants at 6 months of age have better haematological parameters if they have delayed cord clamping, compared with those who had early cord clamping (van Rheenan and Brabin, BMJ 2006;333:954–8). Superior iron stores from the placental blood reaching the neonate lead to improved childhood survival in resource-poor settings.

The authors recommended 3 minutes delay from delivery to clamping, with the infant at the same level as the mother (±10 cm). Lowering the baby speeds blood crossing from the placenta.

There are various theoretical objections to delayed cord clamping, but these are dealt with as follows:

  • • 
    Preterm infants may be polycythaemic and could be at risk from hyperbilirubinaemia if extra blood crosses to the neonate. There is no evidence from trials to support this possibility, and no infants required phototherapy in the studies published.
  • • 
    Growth-restricted fetuses can be polycythaemic from chronic hypoxia, but again the trials of delayed clamping show no adverse effects. In developing countries, such babies have low ferritin levels, strengthening the case for delayed clamping.
  • • 
    The active management of the third stage of labour could be compromised by delayed clamping. The use of oxytocics to reduce blood loss is not affected by delayed clamping, and the combination is beneficial to mother and baby.
  • • 
    When neonatal resuscitation is needed, delayed clamping is also acceptable. When assisted ventilation is required, this decision is usually taken at 60 seconds, during which time the infant should be placed between the mother’s legs and given oxygen.

A strong case for delayed clamping at 3 minutes of age can be made for all deliveries in developing countries. The marginal benefits in wealthier nations may mean resistance to change entrenched labour ward habits, despite the fact that early clamping is an artificial intervention. It will be interesting to watch institutional responses to this new information.

Dental health and preterm birth

  1. Top of page
  2. Older mothers
  3. Amniocentesis and pregnancy loss
  4. New contraceptive use
  5. Twins and intelligence
  6. Breastfeeding and intelligence
  7. When to clamp the cord
  8. Dental health and preterm birth

Delivery before 37 weeks accounts for 12% of births in developed countries. This figure is not decreasing despite cerclages for short cervices, antibiotics for vaginosis and tocolytics for preterm contractions. In fact, even where risk situations are identified, interventions are not effective.

Periodontal disease has been associated with preterm delivery, possibly by oral pathogens seeding the placenta, leading to subclinical chorioamnionitis and prostaglandin release. To test the theory that better dental hygiene would lead to fewer preterm births, Michalowicz et al. from Minnesota (NEJM 2000;355:1885–94) carried out periodontal cleaning and plaque removal followed by regular care thereafter on half of a group of pregnant women while treating the controls after delivery.

The intervention, which was early in the second trimester, resulted in healthier teeth but did not alter the preterm delivery rate, so by all means encourage dental health-care; it is safe in pregnancy but seems unlikely to affect the length of gestation.

Footnotes
  1. These snippets are extracts from a monthly service called the Journal Article Summary Service. It is a service that summarises all that is new in obstetrics and gynaecology over the preceding month. If you would like to know the details of how to subscribe, please email the editor Athol Kent at atholkent@mweb.co.za or visit the website www.jassonline.com.