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Making a baby

An introduction into how the person our child will become has been hugely influenced by decisions made long before they are born.

By the time a baby is born a lot has already happened in shaping and determining their future. A multitude of factors will have already impacted on the child’s physical, socio-emotional and intellectual development before they take their first breath of air. Many of these factors we may have little or no control over but for the prospective parent there is much that they can do to give their child the best possible start. Having a greater understanding of all of the pre-birth factors can help us to make informed decisions and consider what changes we might want to make when planning to have a child. It is however really important to recognise that these influences on our unborn children are probabilities not certainties. If I eat only chocolate there is a good probability that I will become obese, develop diabetes and have increased risk of coronary heart disease but they are not 100% certain to happen. Equally, an adverse influencing factor does not necessarily mean an adverse outcome for the child.


Conception and Gender

The moment of conception is when a sperm from the male reaches and enters the ovum from the female. This usually occurs several hours after intercourse. It is at this point that gender is determined as the successful sperm out of the many that entered the ‘race’ will carry either an X chromosome meaning that the baby will be a girl or a y-chromosome to make a boy. Some research suggests that the timing of intercourse can have an influence over whether a male or female producing sperm is more likely to succeed. The theory proposes that ‘female’ sperm are slower but have longer lives than ‘male’ sperm. During the menstrual cycle once an ovum has been released it moves slowly down the fallopian tube towards the cervix. ‘Female’ sperm may be better at reaching an ovum closer to the ovary whilst the ‘male’ sperm may be more likely to tire and die. When the ovum is closer to the cervix the ‘male’ sperm being faster tend to get there first. An alternative theory suggests that the PH balance (how acidic or not) of the secretions produced by the woman determine gender. This research provides some evidence that ‘female’ sperm are more resilient to more acidic conditions and are able to survive to enable conception. Where the conditions are more favourable the ‘male’ sperm tend to succeed. This theory may in part explain why some women only give birth to boys or only give birth to girls in spite of having several children.


Deoxyribonucleic Acid - DNA

One factor that parents have no control over is their DNA. Females have two x-chromosomes whilst males have only one x-chromosome and a y-chromosome. The y-chromosome, other than determining male gender, is much less important than the x-chromosome in terms of the function of the DNA. Thus for males they need their x-chromosome to be perfect. Women are more fortunate, if part of their DNA is damaged they can use their other x-chromosome to resolve the problem. This is why males are much more likely to have consequences of DNA damage. It may also explain why many developmental conditions such as autism are more prevalent in boys than girls. More than three-quarters of miscarriages are thought to involve male foetuses and males generally have a higher mortality rate in childhood. Advances in screening, DNA testing and new techniques for repairing DNA are being developed and may give prospective parents greater control over their DNA in the future. However, there is interesting research suggesting that even where DNA is perfectly intact it is never all active. Some bits (genes) are switched on and some are off. More importantly, environmental factors can determine whether a gene is on or off.

A woman is born with all her eggs that she will need already formed. During pregnancy a female girl will create her sex cells and the DNA becomes fixed at the point. More importantly encoded within the DNA will be an epigenetic record of the socio-economic risk affecting the girl’s mother at that time. What this means is that if the times are good or bad for the girl’s mother then certain genes will be either switched on or off. The effect of these gene expressions will influence the child’s behaviour through life. For males, there is a similar process but it occurs when a boy reaches puberty. Though sperm are produced throughout life they are essentially copies of sex cells that become fixed at puberty. Again there is evidence that gene expression reflects the socio-economic risk for that boy and his family at the time of puberty. This will then influence the behaviour of any children the boy will subsequently have. These influences stored in sex cells thus skip a generation, and so we inherit them from our grandparents rather than our parents. They may have an evolutionary function in helping to communicate survival information to future generations. A child is a product of two parents DNA so these influences are small. However, where there are major societal disturbances such as prolonged war and danger or famine and food shortage these are likely to influence attitudes and behaviour towards food and other behaviours such as the age of becoming parents.


Older Parents

In the developed world people are becoming parents later and this has some positive and negative repercussions. On the positive side older parents are generally more economically secure, have their own home and relationships are more established. On the negative side leaving it later to start a family increases the chances of complications and problems with conceiving, pregnancy and the health, education and well-being of the child. It is important to recognise that these risks are still very small but they do increase with age and are particularly relevant to those who wait to their forties and fifties. Women are born with their eggs and though the DNA can degenerate slowly with age they are more likely to be 'good' until the menopause. In men, research suggests that sperm may be more vulnerable to DNA degeneration. As a consequence of being made each day the sex cells are repeatedly copying themselves and this process leads to increased likelihood of mutations and other copying error damage. It has been estimated that there is one copying error for each year past twenty years. So though there is no biological barrier to prevent men fathering when they are seventy the chances of a healthy child, particularly boys, is increasingly doubtful.