Thatchers Thoughts: Age
Age related increase in uterine dysfunction during labor
Title: The relationship between maternal age and uterine dysfunction: A continuous effect throughout reproductive life
Author: D. Main, et al.
Address: San Francisco, CA
Source: American Journal of Obstetrics and Gynecology 183:1312-1320 (November) 2000
Summary: This study was undertaken to determine whether there is a continuous effect of maternal age on uterine function. Using a comprehensive computerized database and medical record system, researchers identified 8496 low risk patients who were nulliparous and in spontaneous term labor with singleton fetuses in vertex presentation. Subjects were analyzed according to maternal age for measures of labor dysfunction and rates of operative delivery. The use of oxytocin, duration of second stage of labor, cesarean delivery, cesarean delivery for failure to progress and operative vaginal delivery rates were significantly increased with advancing maternal age. These increases appeared to be continuous functions beginning during the early 20s instead of a new phenomenon beginning after age 35. Researchers concluded that among nulliparous patients with uncomplicated labor there is a continuously increasing risk of uterine dysfunction related to maternal age.
Comment: On analysis of a large number of studies on the adverse effects of aging on pregnancy and labor, there are three risks that seem to stand out as incontrovertible. There is an increased risk of spontaneous abortion / chromosomal abnormalities and there is an increased risk of C-section. Some have stated this is because of the increased incidence of fibroids and anatomic abnormalities. Others have proposed that there is a greater propensity for the obstetrician to intervene because of perceived risk. When both of these are excluded, C-section rates are still higher and seem to be related to uterine dysfunction.
Title: Increasing paternal age is associated with delayed conception in a large population of fertile couples: Evidence of declining fecundity in older men
Author: W. C. Ford, et al.
Address: Bristol, UK
Source: Human Reproduction 15:1703-1708 (August) 2000
Summary: Because controversy continues to surround the issue of aging and male fertility, researchers conducted this study to determine the effect of male age on the length of time it takes to conceive. This study is based on pregnancies that resulted in the birth of a baby. Both the male and female partners completed questionnaires at 18 weeks gestation. The questions were related to such topics as parity, paternity, cohabitation, oral contraception, education, smoking and obesity. Out of 8515 planned pregnancies, 74% were conceived in £6 months, 14% in the second 6 months and 12% after more than a year. After adjustment for 9 different variables, including the age of the woman, the likelihood of conception within 6 or 12 months was lower in older men. Compared to men less than 25 years old, the adjusted odds ratios for conception £12 months were 0.62 in men aged 30-34, 0.50 in men 35-39, and 0.51 in men >40 years of age.
Comment: Still not too bad for the old men.
Uterine responsiveness and reproductive aging
Title: Pregnancy after embolization of uterine myoma: report of 12 cases
Author: J. H. Check, et al.
Address: Camden, New Jersey
Source: Human Reproduction 15: 1679-1684 (August) 2000
Summary:The purpose of this study was to determine if uterine vascular impedance escalates with aging in women experiencing ovarian stimulation for IVF. Women (n=162) who had undergone standard IVF and embryo transfer were divided into three subgroups according to age: 30-34 years (n=49), 35-39 years (n=79), and 40-44 years (n=34). Pulsatility index (PI) and resistance index (RI) of the right and left uterine arteries were measured at baseline, the day of oocyte retrieval, and at mid-luteal phase. The luteal phase values of PI and RI were lower than those observed earlier in the cycle for all groups. Ovarian response, as measured by mean number of oocytes retrieved, declined significantly with age. Researchers concluded that reduced pregnancy rates in older women undergoing ovarian stimulation are more likely to occur because of oocyte quality and quantity rather than uterine senescence.
Comment: More support for the issue of fertility rests more with egg and therefore, embryo quality than that of the uterus.
Maternal age and risk of type 1 diabetes
Title: Influence of maternal age at delivery and birth order on risk of type 1 diabetes in childhood: prospective population based family study
Author: P. Bingley, et al.
Address: Bristol, England
Source:British Medical Journal 321: 420-424 (August) 2000
Summary: In a prospective population based family study, researchers studied the impact of parental age at delivery and birth order on subsequent risk of childhood diabetes. Subjects were 1375 families in which one child or more had diabetes. Of 3221 offspring, 1431 had diabetes and 1790 remained non-diabetic at a median age of 16.1 years. It was discovered that maternal age at delivery was strongly related to the risk of type 1 diabetes in the offspring. The risk increased by 25% for each five year increase of maternal age, so that maternal age at delivery of greater than or equal to 45 years was associated with a relative risk of 3.11 when compared with a maternal age of less than 20 years. Paternal age was also associated with a 9% increase for each five year increase in paternal age. However, the relative risk of diabetes, adjusted for parental age at delivery and sex of offspring, decreased with increasing birth order. The overall effect was a 15% risk reduction per child born. Researchers speculated that the increase in maternal age at delivery in the United Kingdom over the past two decades could partly account for the rise in incidence of childhood diabetes over this period.
Comment: A curious association, but a mechanism is still lacking.