NUTR2003 Lecture Notes - Lecture 5: Anencephaly, Menorrhagia, Teratology
NUTR2003 LECTURE FOUR
PRECONCEPTION
Preconception or periconceptional period:
• Period around the time of conception generally defined as the month before and the month after
conception
Facts:
4/10 pregnancies worldwide are unplanned (difficult to intervene)
Perinatal deaths are 50% higher among babies born to adolescent mothers
Up to 10% of pregnancies among women with untreated gonococcal infections result in perinatal death
Life course - when to intervene?
• Ideally throughout lifestyle, i.e. at most vulnerable stages and PRECONCEPTION PERIOD
• School age and adolescence (reproduction)
• Adulthood (reproduction)
Preconception care:
• Biomedical, behavioural and social health interventions to women and couples before conception
occurs
• Aims at improving health status and reducing behaviours and individual and environmental factors
that could contribute to poor maternal and child health outcomes
• Its ultimate aim is improved maternal and child health outcomes in the short and long term
Prevention of negative outcomes (examples):
Child mortality
Birth defects
Preterm birth
Macrosomia (large babies)
Goitre
Hypothyroidism
Underweight and stunting
Low birth weight
Maternal mortality
Childhood cancers
Key Nutrition Concepts:
• Fertility (ability to become and maintain pregnancy)
• Oral contraceptives and contraceptive implants
• Optimal nutritional status prior to pregnancy
• Before and during the first two months after conception influence embryonic development and the
risk of complications during pregnancy
Pregnancy: a continuum, from preconception to post-partum period
• Usually 40 weeks
• Weeks 1-12 = 1st trimester
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• Foetal period= 12-40 weeks
• Preconception period: 1-2 years prior to conception
Fecundity: Biological ability to bear children
Infertility: Inability to have children after 1 year of unprotected sex
• ~15% couples infertile - involuntarily childless
• 40% diagnosed will conceive within 3 years without technology
• Healthy couples 23-30% pregnancy within given menstrual cycle
Miscarriage: loss of conceptus in 1st 2 weeks pregnancy
Causes:
• Defect in foetus
• Maternal infection
• Structural abnormalities uterus
• Endocrine or immunological disturbances
Subfertility: reduced level of fertility characterised by unusually long time for ception (over 12 motnsh)
~18% of couples
E.g. infrequent ovulation, sperm abnormalities, having multiple miscarriages
Health conditions: POLYCYSTIC OVARIAN SYNDROME
• Ovaries produced high levels androgens
• Can be managed with diet
• Associated with abdominal obesity and insulin resistance (foods with low GI**; weight loss of <5%
makes a difference)
** How quickly insulin is secreted in response to carbohydrates
Reproductive Physiology:
• Development begins during first months after conception and continue to grow and develop
throughout puberty
• Capacity for reproduction establishes during puberty with hormonal changes (biologically capable)
• Women born with lifetime supple of ~7 million ova
• ~400-500 ova will mature and be released during fertile years
• Chromosomes in ova may be damaged by oxidation, radioactive particle exposure, ageing
• Women >35 years more likely to have chromosomal defects than younger women
Sperm production beings during puberty, decreases somewhat after age 35 with production continuing
to old age
• Interactions among hypothalamus, pituitary gland and tested produce androgens
• Testosterone stimulates maturation of sperm
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