As an early pioneer of the elderly primagravida club, I now find that my menopause coincides with my daughter's adolescence. She blossoms; my flower is fading. She looks forward to a life full of nothing but promise; I look back with the inevitable disappointments of middle age. She wants Radio 1 on in the car; I have developed a chilling preference for Radio 2. She bounds up the stairs with ease, wants to wallow in her new sexuality and go out dancing all night. I am beginning to creak with aching joints as the oestrogen plummets. Most nights, I am so knackered that my new best thing is going to bed.
Inevitably, fluctuating hormones and polarised expectations create numerous opportunities for conflict. We can both be incredibly grumpy at times, vague and forgetful when we are premenstrual and consequently, like all mothers and teenage daughters, we have the odd spat. But the fact that we now have so much more in common with one another as women, even though we are at opposite ends of the menstrual spectrum feels far more significant. And, if I am to be grown-up about it (which can be hard in middle age), it is how I feel about myself - old and boring - as I watch her turning into a beautiful, capable and confident young woman, which creates the potential minefield. I am the one with the problems that need to be capped, not her.
As our bodies mature, we have both become preoccupied with microscopic physical changes. She laments her "chicken skin" now that the satin surface of childhood has thickened with maturity, and every tiny spot feels as big as a lighthouse. I look with hate at my cellulite and at the cruel way that middle age drags every bit of flesh out and down. I look at her beautiful lithe body, her firm flat stomach and cannot help but envy her voluptuousness and mourn what I have lost. I feel myself mutating physically into the mother I had as a teenager, and marvel at my own daughter's tact and kindness. She never says a thing.
The feeling of never having anything to wear is not exclusive to teenage girls. Finding the right style at these times of great physical change is difficult for both of us. Do I progress up the style ladder of age with suits and slacks, or attempt to maintain the fiction of youth with jeans and Converse shoes? When we go shopping together, we both try on dozens of different outfits, trying to find the right look, and always end up buying the same things - she can never have enough jeans and skimpy tops; I always need another flattering black jumper. And then, when it comes to sex, we are both stumped. She is just beginning to feel her way with boys; I look down at my body, which feels increasingly as if it has nothing to do with the real me and wonder who on earth could possibly want it should my happy, stable marriage fail.
The life stages of adolescence and middle age mirror each other in deeper ways, too. We are both at a crossroads. She can see her life stretching way ahead of her and has to think seriously about what she wants to do with it, no mean feat now that she is aware how the wrong decision or choice of A-levels could take her down the wrong path. I contemplate the time I have left as the children begin to need me less and question what I will do with these precious years.
Inevitably at 46, I have regrets, dreams I have wanted to pursue which may now never happen. And then I look at my daughter with so much life stretching ahead of her and it is not that I envy her, more that I don't want her to waste a single moment. I want her life to be richer in every way than mine has been and risk accusations of being a pushy mother as a result.
We have both found a new confidence to speak our mind, which can be irritating. She is rightly passionate and idealistic about the state of the world and likes to test her critical wings. She also feels it is her God-given right to talk or ask questions while I'm watching the news or interesting programmes about art or culture. I now embarrass my children by chatting with shopkeepers, hurling abuse at other motorists and arguing with people who annoy me. Life feels just too short now not to be able to enjoy this privilege and I no longer care what other people think of me, much.
I also feel like a nag for the first time in my life. Why is it that with middle age, I have suddenly started to care about things such as tidiness, how the house looks and whether or not the butter knife goes into the marmalade? My daughter doesn't think those things matter. I never used to think those sort of things mattered. They don't really. It is not just that she is untidy (which she is, few teenagers aren't); it is the way her untidiness makes me feel so much older than I want to be because this sort of trivia crops up in conversation, like it used to with my own mother and grandmother when I was her age.
Nothing escapes her new discriminating eye (my state of dress, the sparse contents of the biscuit tin), or mine, for that matter (the way newly ironed clothes become instantly dishevelled, spilling out of her drawers as she burrows to the bottom, or the fact that she is leaving the house wearing my expensive sheer tights again).
And then there is the anxiety, which is, of course, motherhood's middle name. When adolescence and middle age coincide, anxiety levels go into orbit. Teenagers venture out into a world full of drugs, binge-drinking, sexual promiscuity, venereal disease and street crime, at a time when parents begin to feel frailer and that much more aware of their own mortality. I have worried about everything since the day she was born, but now that she is 15 and I am 46, I worry that much more.
The stability that comes from having parents who will always be there for you is shifting slowly for both of us. She now imagines a future without us, which is scary and exciting at the same time; I am losing the security that comes from having parents for good. My father died last year and as my mother grows older, she needs me more. Consequently friendships really matter. My daughter needs her friends as she ventures out into the world alone. She feels, and is, safer surging along the streets in packs or coming home from a party at night with a friend. As I grow older, the friendships that have lasted since my teens mean more to me than ever. These trusted, loving souls have stood by me and accepted my many faults as well as my strengths, and feel like family now.
But there is one overwhelming feeling that is mine alone - the acute sadness that comes from losing my fertility as well as the child I have loved more than life itself. While my daughter experiences the great gains of becoming a young woman with the loss of childhood, I have merely loss - loss of youth, energy and most importantly the tiny cherub who is now too big to sit on my lap. For the first time in 15 years of being a mother, I no longer feel that sublime umbilical connection. She is my daughter and I love her passionately, but she no longer feels like the flesh of my flesh. I look at mothers with their small children and envy them sometimes. It has all passed so quickly. We may both be emotionally volatile, but I'm the one usually doing the crying now in our house, not the children.
Perhaps that is the overwhelming reason why we spend more time curled up in front of the telly together than rowing over the state of her room. I need her to feel that her home is still here for her, a welcome sanctuary from the strain of looking good and making it in the big wide world. I need us to stay close.
The years spent researching adolescent development for my book The Terrible Teens have helped, for I now recognise typical teenage behaviour and rise less to the futility of challenging it. But there are still times when I lose it, exasperated by the mess, by the way everything I own is up for grabs, by the way I'm made to feel so old and boring beside her vibrant youth and beauty - what menopausal woman wouldn't. But there are also immense new pleasures to be gained from watching her blossom into her own woman, full of confidence, ambition and kindness. As I feel my mental horizons constricting with age, I need her to challenge me with the vibrant, passionate idealism of youth. I can perhaps be reminded to stay young at heart. And I always did want to spend more time on the garden.
· Kate Figes' novel What About Me? - The Diaries and emails of a Menopausal Mother and Her Teenage Daughter is published by Macmillan on Friday at £14.99
