D. M. Campbell

Effect of B vitamins and genetics on success of in-vitro fertilisation: prospective cohort study

BACKGROUND There is a need to understand what affects the success of in-vitro fertilisation (IVF) and the rate of resulting twin births so that pregnancy rates can be improved and multiple gestations avoided. Our aim was to assess the role of B vitamins and genetics. METHODS We did a prospective cohort study of 602 women undergoing fertility treatment. We assessed intake of folate and vitamin B12 with a questionnaire and measured their plasma and red-blood-cell concentrations by radioimmunoassay. We measured five B-vitamin-related gene variants in women who received treatment and in 932 women who conceived naturally. FINDINGS The likelihood of a twin birth after IVF rose with increased concentrations of plasma folate (1.52, 1.01-2.28; p=0.032) and red-cell folate (1.28, 1.00-1.65; p=0.039). There was no association between folate and vitamin B12 levels and likelihood of a successful pregnancy. Women homozygous for the 1298 CC variant of methylenetetrahydro-folate reductase (MTHFR), rather than the AA variant, were less likely to produce a livebirth after IVF (0.24, 0.08-0.71; p=0.003) or to have had a previous pregnancy (0.42, 0.21-0.81; p=0.008). INTERPRETATION Our findings suggest that MTHFR genotype is linked to a womans potential to produce healthy embryos (possibly through interaction with genes related to DNA methylation). In women likely to have a successful IVF pregnancy, high folate status increases the likelihood of twin birth after multiple embryo transfer. Proposals to fortify the UK diet with folic acid could lead to an increase in the number of twins born after IVF.

Mode of delivery and future fertility

A cohort of 22 948 women from a stable homogeneous population who gave birth for the first time between 1964 and 1983 were followed up prospectively. Analysis by mode of delivery showed that of those delivered by caesarean section 23·2% fewer had another pregnancy than those who had a spontaneous vaginal delivery. Women delivered by forceps were in an intermediate group. Miscarriage was more common in women who had been delivered by caesarean section. The relative infertility after caesarean section could not be accounted for by early sterilization, was not associated with maternal height or social status, and was only partly attributable to age.

Beta‐human chorionic gonadotrophin levels before and after the development of pre‐eclampsia

Summary. Maternal serum levels of beta‐human chorionic gonadotrophin ((β‐hCG) concentrations were significantly higher in 41 primigravid patients with proteinuric pre‐eclampsia compared with those in 41 primigravid normotensive women matched for age and gestation. β‐hCG was also measured in serial serum samples obtained from 13 women who had a high weight‐gain between 20 and 30 weeks of pregnancy. Seven of these pregnancies were subsequently complicated with pre‐eclampsia while the remaining six continued to be normotensive; β‐hCG levels were found to rise before the clinical signs of pre‐eclampsia appeared.

TOXIC HAEMOLYTIC ANAEMIA IN PREGNANCY DUE TO A PICA FOR PARADICHLOROBENZENE

A pregnant woman developed toxic haemolytic anaemia as a result of a pica for toilet air‐freshener blocks whose chief constituent is paradichlorobenzene.

Ponderal index is a poor predictor of in utero growth retardation

Objective  To evaluate the usefulness of ponderal index (PI) and related indices of weight and length in identifying asymmetric growth, body thinness and organ asymmetry associated with IUGR.

Blood levels of proteinase inhibitors in pregnancy

Summary. Plasma volume, serum α2‐macroglobulin, α1‐antitrypsin, Cï inactivator and α2‐antiplasmin, and plasma antithrombin III were measured in 10 pregnant women at gestation periods of 12–14 and 37–38 weeks. The proteinase inhibitors were also measured in 10 non‐pregnant healthy women. There was a significant increase in the α1‐antitrypsin concentration and significant decreases in α2‐macroglobulin and Cï inactivator, but the total circulating quantity of all the proteinase inhibitors was significantly increased.

Blood levels of proteinase inhibitors in pre‐eclampsia

Summary. The blood levels of α2‐macroglobulin, α1‐antitrypsin, CT inactivator, antithrombin III and α2‐antiplasmin were measured in 18 primigravidae with moderate or severe pre‐eclampsia and in 18 gestation‐matched primigravidae with uncomplicated pregnancy. The mean levels of the proteinase inhibitors did not differ between the pre‐eclampsia and uncomplicated pregnancy groups.

Folic acid use in pregnancy and embryo selection

Objective  Folic acid supplement use is recommended in pregnancy to reduce the risk of neural tube defect but concerns have been raised that increasing folic acid intake may select for embryos with genotypes that increase disease risk in the offspring. Our aim was to test for this effect.

B-vitamin intake in human pregnancy and imprinted gene methylation in the offspring

It has been proposed that altered epigenetic status at imprinted loci may play a role in the early programming of disease susceptibility (1) . The ultimate methyl donor for methylation reactions is the folate-methylation cycle and feeding pregnant dams diets deficient in methyl donors results in altered regulation of specific genes in the offspring which are under imprinting control (2) . The aim of this study was to determine whether a similar phenomenon may occur in human pregnancy. The study was approved by Grampian Research Ethics Committee and all participants gave informed written consent. We collected data on dietary and supplement intake and cord blood DNA from pregnancies sequentially recruited at Aberdeen Maternity Hospital. Energyadjusted intake of the B-vitamins (thiamine, niacin, biotin, riboflavin, folate, B6 and B12) from the diet was assessed at 19 weeks gestation using a self-administered food frequency questionnaire (3) . The use of folic acid supplements (type/brand, amount per day, timing and duration of consumption in relation to stage of pregnancy) were also recorded. Multiple methylation sites were measured in three imprinted genes (IGF2, n 374; SNRPN, n 363; PEG3, n 377) and LINE1 (n 372) which was thought to contribute to the differential expression of paternally and maternally imprinted genes. Methylation was determined by pyrosequencing using a PyroMark MD system (Qiagen, Crawley, UK) after bisulphite conversion of DNA using Epitect Bisulfite kits (Qiagen, Crawley, UK). Statistical analysis was carried out using STATA 11MP (Stata Corp, College Station, TX, USA). All the B vitamins from diet were included in the regression model. There was no evidence that dietary intake of B vitamins was related to LINE1 or SNRPN methylation. Dietary intake of riboflavin, vitamin B6 and folate were associated with the average methylation status of both IGF2 (riboflavin, P = 0.012; vitamin B6, P = 0.047; folate, P = 0.024; model r 2 = 3.9%) and PEG3 (riboflavin, P = 0.016; vitamin B6, P = 0.014; folate, P = 0.001; model r 2 = 2.6%). Although responsive to the same nutrients, there were differences between PEG3 and IGF2 in the sign of the response. Separate analysis of supplement use provided no evidence for an effect on the methylation of folic acid intake in line with current advice. The way in which parental diet influences the methylation of individual genes and the health consequences for the offspring merit further study. Further work on this phenomenon in larger numbers of pregnancies is proposed.

Effect of miscarriage on subsequent pregnancies

1 Bhattacharya S, Townend J, Shetty A, Campbell D, Bhattacharya S. Does miscarriage in an initial pregnancy lead to adverse obstetric and perinatal outcomes in the next continuing pregnancy? BJOG 2008;115:1623–9. 2 Batty GD, Morton SM, Campbell D, Clark H, Smith GD, Hall M, et al. The Aberdeen Children of the 1950s cohort study: background, methods and follow-up information on a new resource for the study of life course and intergenerational influences on health. Paediatr Perinat Epidemiol 2004;18:221–39. 3 Everett C. Incidence and outcome of bleeding before the 20th week of pregnancy: prospective study from general practice. BMJ 1997;315:32–34. 4 Lok IH, Neugebauer R. Psychological morbidity following miscarriage. Best Pract Res Clin Obstet Gynaecol 2007;21:229–47.